Use system font stack for fallbacks

R/style_duo.R

 #' @param text_font_family Body Text Font Family (xaringan default is `'Droid Serif'`). Defaults to Noto Sans. Modifies the `body` element.
 #' @param text_font_weight Body Text Font Weight. Defaults to normal. Modifies the `body` element.
 #' @param text_font_url Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the `@import url()` elements.
-#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the `body` element.
-#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the `body` element.
+#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the `body` element.
+#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the `body` element.
 #' @param header_font_google Use `google_font()` to specify header font. Defaults to `NULL`. Modifies the `body` element.
 #' @param header_font_family Header Font Family (xaringan default is `'Yanone Kaffeesatz'`). Defaults to Cabin. Modifies the `h1, h2, h3` elements.
 #' @param header_font_weight Header Font Weight. Defaults to 600. Modifies the `h1, h2, h3` elements.
 #' @param code_font_family Code Font Family. Defaults to Source Code Pro. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @param code_font_size Code Text Font Size. Defaults to 0.9rem. Modifies the `.remark-inline` class.
 #' @param code_font_url Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the `@import url` elements.
-#' @param code_font_family_fallback Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the `.remark-code, .remark-inline-code` classes.
+#' @param code_font_family_fallback Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @template theme_params
 #' @template style_duo
 #' @family Duotone themes
   text_font_family = "Noto Sans",
   text_font_weight = "normal",
   text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
-  text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+  text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_family = "Source Code Pro",
   code_font_size = "0.9rem",
   code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,

R/style_duo_accent.R

 #' @param text_font_family Body Text Font Family (xaringan default is `'Droid Serif'`). Defaults to Noto Sans. Modifies the `body` element.
 #' @param text_font_weight Body Text Font Weight. Defaults to normal. Modifies the `body` element.
 #' @param text_font_url Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the `@import url()` elements.
-#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the `body` element.
-#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the `body` element.
+#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the `body` element.
+#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the `body` element.
 #' @param header_font_google Use `google_font()` to specify header font. Defaults to `NULL`. Modifies the `body` element.
 #' @param header_font_family Header Font Family (xaringan default is `'Yanone Kaffeesatz'`). Defaults to Cabin. Modifies the `h1, h2, h3` elements.
 #' @param header_font_weight Header Font Weight. Defaults to 600. Modifies the `h1, h2, h3` elements.
 #' @param code_font_family Code Font Family. Defaults to Source Code Pro. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @param code_font_size Code Text Font Size. Defaults to 0.9rem. Modifies the `.remark-inline` class.
 #' @param code_font_url Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the `@import url` elements.
-#' @param code_font_family_fallback Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the `.remark-code, .remark-inline-code` classes.
+#' @param code_font_family_fallback Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @template theme_params
 #' @template style_duo_accent
 #' @family Duotone themes
   text_font_family = "Noto Sans",
   text_font_weight = "normal",
   text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
-  text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+  text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_family = "Source Code Pro",
   code_font_size = "0.9rem",
   code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,

R/style_duo_accent_inverse.R

 #' @param text_font_family Body Text Font Family (xaringan default is `'Droid Serif'`). Defaults to Noto Sans. Modifies the `body` element.
 #' @param text_font_weight Body Text Font Weight. Defaults to normal. Modifies the `body` element.
 #' @param text_font_url Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the `@import url()` elements.
-#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the `body` element.
-#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the `body` element.
+#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the `body` element.
+#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the `body` element.
 #' @param header_font_google Use `google_font()` to specify header font. Defaults to `NULL`. Modifies the `body` element.
 #' @param header_font_family Header Font Family (xaringan default is `'Yanone Kaffeesatz'`). Defaults to Cabin. Modifies the `h1, h2, h3` elements.
 #' @param header_font_weight Header Font Weight. Defaults to 600. Modifies the `h1, h2, h3` elements.
 #' @param code_font_family Code Font Family. Defaults to Source Code Pro. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @param code_font_size Code Text Font Size. Defaults to 0.9rem. Modifies the `.remark-inline` class.
 #' @param code_font_url Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the `@import url` elements.
-#' @param code_font_family_fallback Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the `.remark-code, .remark-inline-code` classes.
+#' @param code_font_family_fallback Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @template theme_params
 #' @template style_duo_accent_inverse
 #' @family Duotone themes
   text_font_family = "Noto Sans",
   text_font_weight = "normal",
   text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
-  text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+  text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_family = "Source Code Pro",
   code_font_size = "0.9rem",
   code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,

R/style_mono_accent.R

 #' @param text_font_family Body Text Font Family (xaringan default is `'Droid Serif'`). Defaults to Noto Sans. Modifies the `body` element.
 #' @param text_font_weight Body Text Font Weight. Defaults to normal. Modifies the `body` element.
 #' @param text_font_url Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the `@import url()` elements.
-#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the `body` element.
-#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the `body` element.
+#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the `body` element.
+#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the `body` element.
 #' @param header_font_google Use `google_font()` to specify header font. Defaults to `NULL`. Modifies the `body` element.
 #' @param header_font_family Header Font Family (xaringan default is `'Yanone Kaffeesatz'`). Defaults to Cabin. Modifies the `h1, h2, h3` elements.
 #' @param header_font_weight Header Font Weight. Defaults to 600. Modifies the `h1, h2, h3` elements.
 #' @param code_font_family Code Font Family. Defaults to Source Code Pro. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @param code_font_size Code Text Font Size. Defaults to 0.9rem. Modifies the `.remark-inline` class.
 #' @param code_font_url Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the `@import url` elements.
-#' @param code_font_family_fallback Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the `.remark-code, .remark-inline-code` classes.
+#' @param code_font_family_fallback Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @template theme_params
 #' @template style_mono_accent
 #' @family Monotone themes
   text_font_family = "Noto Sans",
   text_font_weight = "normal",
   text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
-  text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+  text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_family = "Source Code Pro",
   code_font_size = "0.9rem",
   code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,

R/style_mono_accent_inverse.R

 #' @param text_font_family Body Text Font Family (xaringan default is `'Droid Serif'`). Defaults to Noto Sans. Modifies the `body` element.
 #' @param text_font_weight Body Text Font Weight. Defaults to normal. Modifies the `body` element.
 #' @param text_font_url Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the `@import url()` elements.
-#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the `body` element.
-#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the `body` element.
+#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the `body` element.
+#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the `body` element.
 #' @param header_font_google Use `google_font()` to specify header font. Defaults to `NULL`. Modifies the `body` element.
 #' @param header_font_family Header Font Family (xaringan default is `'Yanone Kaffeesatz'`). Defaults to Cabin. Modifies the `h1, h2, h3` elements.
 #' @param header_font_weight Header Font Weight. Defaults to 600. Modifies the `h1, h2, h3` elements.
 #' @param code_font_family Code Font Family. Defaults to Source Code Pro. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @param code_font_size Code Text Font Size. Defaults to 0.9rem. Modifies the `.remark-inline` class.
 #' @param code_font_url Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the `@import url` elements.
-#' @param code_font_family_fallback Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the `.remark-code, .remark-inline-code` classes.
+#' @param code_font_family_fallback Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @template theme_params
 #' @template style_mono_accent_inverse
 #' @family Monotone themes
   text_font_family = "Noto Sans",
   text_font_weight = "normal",
   text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
-  text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+  text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_family = "Source Code Pro",
   code_font_size = "0.9rem",
   code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,

R/style_mono_dark.R

 #' @param text_font_family Body Text Font Family (xaringan default is `'Droid Serif'`). Defaults to Noto Sans. Modifies the `body` element.
 #' @param text_font_weight Body Text Font Weight. Defaults to normal. Modifies the `body` element.
 #' @param text_font_url Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the `@import url()` elements.
-#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the `body` element.
-#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the `body` element.
+#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the `body` element.
+#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the `body` element.
 #' @param header_font_google Use `google_font()` to specify header font. Defaults to `NULL`. Modifies the `body` element.
 #' @param header_font_family Header Font Family (xaringan default is `'Yanone Kaffeesatz'`). Defaults to Cabin. Modifies the `h1, h2, h3` elements.
 #' @param header_font_weight Header Font Weight. Defaults to 600. Modifies the `h1, h2, h3` elements.
 #' @param code_font_family Code Font Family. Defaults to Source Code Pro. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @param code_font_size Code Text Font Size. Defaults to 0.9rem. Modifies the `.remark-inline` class.
 #' @param code_font_url Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the `@import url` elements.
-#' @param code_font_family_fallback Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the `.remark-code, .remark-inline-code` classes.
+#' @param code_font_family_fallback Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @template theme_params
 #' @template style_mono_dark
 #' @family Monotone themes
   text_font_family = "Noto Sans",
   text_font_weight = "normal",
   text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
-  text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+  text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_family = "Source Code Pro",
   code_font_size = "0.9rem",
   code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,

R/style_mono_light.R

 #' @param text_font_family Body Text Font Family (xaringan default is `'Droid Serif'`). Defaults to Noto Sans. Modifies the `body` element.
 #' @param text_font_weight Body Text Font Weight. Defaults to normal. Modifies the `body` element.
 #' @param text_font_url Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the `@import url()` elements.
-#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the `body` element.
-#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the `body` element.
+#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the `body` element.
+#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the `body` element.
 #' @param header_font_google Use `google_font()` to specify header font. Defaults to `NULL`. Modifies the `body` element.
 #' @param header_font_family Header Font Family (xaringan default is `'Yanone Kaffeesatz'`). Defaults to Cabin. Modifies the `h1, h2, h3` elements.
 #' @param header_font_weight Header Font Weight. Defaults to 600. Modifies the `h1, h2, h3` elements.
 #' @param code_font_family Code Font Family. Defaults to Source Code Pro. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @param code_font_size Code Text Font Size. Defaults to 0.9rem. Modifies the `.remark-inline` class.
 #' @param code_font_url Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the `@import url` elements.
-#' @param code_font_family_fallback Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the `.remark-code, .remark-inline-code` classes.
+#' @param code_font_family_fallback Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @template theme_params
 #' @template style_mono_light
 #' @family Monotone themes
   text_font_family = "Noto Sans",
   text_font_weight = "normal",
   text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
-  text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+  text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_family = "Source Code Pro",
   code_font_size = "0.9rem",
   code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,

R/style_solarized_dark.R

 #' @param text_font_family Body Text Font Family (xaringan default is `'Droid Serif'`). Defaults to Noto Sans. Modifies the `body` element.
 #' @param text_font_weight Body Text Font Weight. Defaults to normal. Modifies the `body` element.
 #' @param text_font_url Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the `@import url()` elements.
-#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the `body` element.
-#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the `body` element.
+#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the `body` element.
+#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the `body` element.
 #' @param header_font_google Use `google_font()` to specify header font. Defaults to `NULL`. Modifies the `body` element.
 #' @param header_font_family Header Font Family (xaringan default is `'Yanone Kaffeesatz'`). Defaults to Cabin. Modifies the `h1, h2, h3` elements.
 #' @param header_font_weight Header Font Weight. Defaults to 600. Modifies the `h1, h2, h3` elements.
 #' @param code_font_family Code Font Family. Defaults to Source Code Pro. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @param code_font_size Code Text Font Size. Defaults to 0.9rem. Modifies the `.remark-inline` class.
 #' @param code_font_url Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the `@import url` elements.
-#' @param code_font_family_fallback Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the `.remark-code, .remark-inline-code` classes.
+#' @param code_font_family_fallback Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @template theme_params
 #' @template style_solarized_dark
 #' @family Solarized themes
   text_font_family = "Noto Sans",
   text_font_weight = "normal",
   text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
-  text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+  text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_family = "Source Code Pro",
   code_font_size = "0.9rem",
   code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,

R/style_solarized_light.R

 #' @param text_font_family Body Text Font Family (xaringan default is `'Droid Serif'`). Defaults to Noto Sans. Modifies the `body` element.
 #' @param text_font_weight Body Text Font Weight. Defaults to normal. Modifies the `body` element.
 #' @param text_font_url Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the `@import url()` elements.
-#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the `body` element.
-#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the `body` element.
+#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the `body` element.
+#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the `body` element.
 #' @param header_font_google Use `google_font()` to specify header font. Defaults to `NULL`. Modifies the `body` element.
 #' @param header_font_family Header Font Family (xaringan default is `'Yanone Kaffeesatz'`). Defaults to Cabin. Modifies the `h1, h2, h3` elements.
 #' @param header_font_weight Header Font Weight. Defaults to 600. Modifies the `h1, h2, h3` elements.
 #' @param code_font_family Code Font Family. Defaults to Source Code Pro. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @param code_font_size Code Text Font Size. Defaults to 0.9rem. Modifies the `.remark-inline` class.
 #' @param code_font_url Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the `@import url` elements.
-#' @param code_font_family_fallback Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the `.remark-code, .remark-inline-code` classes.
+#' @param code_font_family_fallback Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @template theme_params
 #' @template style_solarized_light
 #' @family Solarized themes
   text_font_family = "Noto Sans",
   text_font_weight = "normal",
   text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
-  text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+  text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_family = "Source Code Pro",
   code_font_size = "0.9rem",
   code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,

R/style_xaringan.R

 #' @param text_font_family Body Text Font Family (xaringan default is `'Droid Serif'`). Defaults to Noto Sans. Modifies the `body` element.
 #' @param text_font_weight Body Text Font Weight. Defaults to normal. Modifies the `body` element.
 #' @param text_font_url Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the `@import url()` elements.
-#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the `body` element.
-#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the `body` element.
+#' @param text_font_family_fallback Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the `body` element.
+#' @param text_font_base Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the `body` element.
 #' @param header_font_google Use `google_font()` to specify header font. Defaults to `NULL`. Modifies the `body` element.
 #' @param header_font_family Header Font Family (xaringan default is `'Yanone Kaffeesatz'`). Defaults to Cabin. Modifies the `h1, h2, h3` elements.
 #' @param header_font_weight Header Font Weight. Defaults to 600. Modifies the `h1, h2, h3` elements.
 #' @param code_font_family Code Font Family. Defaults to Source Code Pro. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @param code_font_size Code Text Font Size. Defaults to 0.9rem. Modifies the `.remark-inline` class.
 #' @param code_font_url Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the `@import url` elements.
-#' @param code_font_family_fallback Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the `.remark-code, .remark-inline-code` classes.
+#' @param code_font_family_fallback Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the `.remark-code, .remark-inline-code` classes.
 #' @template theme_params
 #' @template style_xaringan
 #' @export
   text_font_family = "Noto Sans",
   text_font_weight = "normal",
   text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
-  text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+  text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_family = "Source Code Pro",
   code_font_size = "0.9rem",
   code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,

R/theme_settings.R

   , "text_font_family", "Noto Sans", "body", "Body Text Font Family (xaringan default is `'Droid Serif'`)"
   , "text_font_weight", "normal", "body", "Body Text Font Weight"
   , "text_font_url", "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap", "@import url()", "Body Text Font URL(s)"
-  , "text_font_family_fallback", "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'", "body", "Body Text Font Fallbacks"
-  , "text_font_base", "serif", "body", "Body Text Base Font (Total Failure Fallback)"
+  , "text_font_family_fallback", "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial", "body", "Body Text Font Fallbacks"
+  , "text_font_base", "sans-serif", "body", "Body Text Base Font (Total Failure Fallback)"
   , "header_font_google", NULL, "body", "Use `google_font()` to specify header font"
   , "header_font_family", "Cabin", "h1, h2, h3", "Header Font Family (xaringan default is `'Yanone Kaffeesatz'`)"
   , "header_font_weight", "600", "h1, h2, h3", "Header Font Weight"
   , "code_font_family", "Source Code Pro", ".remark-code, .remark-inline-code", "Code Font Family"
   , "code_font_size", "0.9rem", ".remark-inline", "Code Text Font Size"
   , "code_font_url", "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap", "@import url", "Code Font URL"
-  , "code_font_family_fallback", "'Lucida Console', Monaco", ".remark-code, .remark-inline-code", "Code Font Fallback"
+  , "code_font_family_fallback", "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console", ".remark-code, .remark-inline-code", "Code Font Fallback"
 )
 
 set_default <- function(tv, ...) {

man/style_duo.Rd

  
     text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
  
-    text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+    text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_size = "0.9rem",
  
     code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,
 
 \item{text_font_url}{Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the \verb{@import url()} elements.}
 
-\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the \code{body} element.}
+\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the \code{body} element.}
 
-\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the \code{body} element.}
+\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the \code{body} element.}
 
 \item{header_font_google}{Use \code{google_font()} to specify header font. Defaults to \code{NULL}. Modifies the \code{body} element.}
 
 
 \item{code_font_url}{Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the \verb{@import url} elements.}
 
-\item{code_font_family_fallback}{Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
+\item{code_font_family_fallback}{Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
 
 \item{colors}{A named vector of custom colors. The names of the colors
 become CSS variables and classes that can be used within your slides.

man/style_duo_accent.Rd

  
     text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
  
-    text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+    text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_size = "0.9rem",
  
     code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,
 
 \item{text_font_url}{Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the \verb{@import url()} elements.}
 
-\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the \code{body} element.}
+\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the \code{body} element.}
 
-\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the \code{body} element.}
+\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the \code{body} element.}
 
 \item{header_font_google}{Use \code{google_font()} to specify header font. Defaults to \code{NULL}. Modifies the \code{body} element.}
 
 
 \item{code_font_url}{Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the \verb{@import url} elements.}
 
-\item{code_font_family_fallback}{Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
+\item{code_font_family_fallback}{Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
 
 \item{colors}{A named vector of custom colors. The names of the colors
 become CSS variables and classes that can be used within your slides.

man/style_duo_accent_inverse.Rd

  
     text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
  
-    text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+    text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_size = "0.9rem",
  
     code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,
 
 \item{text_font_url}{Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the \verb{@import url()} elements.}
 
-\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the \code{body} element.}
+\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the \code{body} element.}
 
-\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the \code{body} element.}
+\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the \code{body} element.}
 
 \item{header_font_google}{Use \code{google_font()} to specify header font. Defaults to \code{NULL}. Modifies the \code{body} element.}
 
 
 \item{code_font_url}{Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the \verb{@import url} elements.}
 
-\item{code_font_family_fallback}{Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
+\item{code_font_family_fallback}{Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
 
 \item{colors}{A named vector of custom colors. The names of the colors
 become CSS variables and classes that can be used within your slides.

man/style_mono_accent.Rd

  
     text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
  
-    text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+    text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_size = "0.9rem",
  
     code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,
 
 \item{text_font_url}{Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the \verb{@import url()} elements.}
 
-\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the \code{body} element.}
+\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the \code{body} element.}
 
-\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the \code{body} element.}
+\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the \code{body} element.}
 
 \item{header_font_google}{Use \code{google_font()} to specify header font. Defaults to \code{NULL}. Modifies the \code{body} element.}
 
 
 \item{code_font_url}{Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the \verb{@import url} elements.}
 
-\item{code_font_family_fallback}{Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
+\item{code_font_family_fallback}{Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
 
 \item{colors}{A named vector of custom colors. The names of the colors
 become CSS variables and classes that can be used within your slides.

man/style_mono_accent_inverse.Rd

  
     text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
  
-    text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+    text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_size = "0.9rem",
  
     code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,
 
 \item{text_font_url}{Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the \verb{@import url()} elements.}
 
-\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the \code{body} element.}
+\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the \code{body} element.}
 
-\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the \code{body} element.}
+\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the \code{body} element.}
 
 \item{header_font_google}{Use \code{google_font()} to specify header font. Defaults to \code{NULL}. Modifies the \code{body} element.}
 
 
 \item{code_font_url}{Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the \verb{@import url} elements.}
 
-\item{code_font_family_fallback}{Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
+\item{code_font_family_fallback}{Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
 
 \item{colors}{A named vector of custom colors. The names of the colors
 become CSS variables and classes that can be used within your slides.

man/style_mono_dark.Rd

  
     text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
  
-    text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+    text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_size = "0.9rem",
  
     code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,
 
 \item{text_font_url}{Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the \verb{@import url()} elements.}
 
-\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the \code{body} element.}
+\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the \code{body} element.}
 
-\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the \code{body} element.}
+\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the \code{body} element.}
 
 \item{header_font_google}{Use \code{google_font()} to specify header font. Defaults to \code{NULL}. Modifies the \code{body} element.}
 
 
 \item{code_font_url}{Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the \verb{@import url} elements.}
 
-\item{code_font_family_fallback}{Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
+\item{code_font_family_fallback}{Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
 
 \item{colors}{A named vector of custom colors. The names of the colors
 become CSS variables and classes that can be used within your slides.

man/style_mono_light.Rd

  
     text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
  
-    text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+    text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_size = "0.9rem",
  
     code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,
 
 \item{text_font_url}{Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the \verb{@import url()} elements.}
 
-\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the \code{body} element.}
+\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the \code{body} element.}
 
-\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the \code{body} element.}
+\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the \code{body} element.}
 
 \item{header_font_google}{Use \code{google_font()} to specify header font. Defaults to \code{NULL}. Modifies the \code{body} element.}
 
 
 \item{code_font_url}{Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the \verb{@import url} elements.}
 
-\item{code_font_family_fallback}{Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
+\item{code_font_family_fallback}{Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
 
 \item{colors}{A named vector of custom colors. The names of the colors
 become CSS variables and classes that can be used within your slides.

man/style_solarized_dark.Rd

  
     text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
  
-    text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+    text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_size = "0.9rem",
  
     code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,
 
 \item{text_font_url}{Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the \verb{@import url()} elements.}
 
-\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the \code{body} element.}
+\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the \code{body} element.}
 
-\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the \code{body} element.}
+\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the \code{body} element.}
 
 \item{header_font_google}{Use \code{google_font()} to specify header font. Defaults to \code{NULL}. Modifies the \code{body} element.}
 
 
 \item{code_font_url}{Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the \verb{@import url} elements.}
 
-\item{code_font_family_fallback}{Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
+\item{code_font_family_fallback}{Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
 
 \item{colors}{A named vector of custom colors. The names of the colors
 become CSS variables and classes that can be used within your slides.

man/style_solarized_light.Rd

  
     text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
  
-    text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+    text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_size = "0.9rem",
  
     code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,
 
 \item{text_font_url}{Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the \verb{@import url()} elements.}
 
-\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the \code{body} element.}
+\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the \code{body} element.}
 
-\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the \code{body} element.}
+\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the \code{body} element.}
 
 \item{header_font_google}{Use \code{google_font()} to specify header font. Defaults to \code{NULL}. Modifies the \code{body} element.}
 
 
 \item{code_font_url}{Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the \verb{@import url} elements.}
 
-\item{code_font_family_fallback}{Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
+\item{code_font_family_fallback}{Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
 
 \item{colors}{A named vector of custom colors. The names of the colors
 become CSS variables and classes that can be used within your slides.

man/style_xaringan.Rd

  
     text_font_url = "https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap",
  
-    text_font_family_fallback = "'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'",
-  text_font_base = "serif",
+    text_font_family_fallback = "-apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial",
+  text_font_base = "sans-serif",
   header_font_google = NULL,
   header_font_family = "Cabin",
   header_font_weight = "600",
   code_font_size = "0.9rem",
  
     code_font_url = "https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap",
-  code_font_family_fallback = "'Lucida Console', Monaco",
+  code_font_family_fallback = "Menlo, Consolas, Monaco, Liberation Mono, Lucida Console",
   colors = NULL,
   extra_css = NULL,
   extra_fonts = NULL,
 
 \item{text_font_url}{Body Text Font URL(s). Defaults to https://fonts.googleapis.com/css?family=Noto+Sans:400,400i,700,700i&display=swap. Modifies the \verb{@import url()} elements.}
 
-\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC'. Modifies the \code{body} element.}
+\item{text_font_family_fallback}{Body Text Font Fallbacks. Defaults to -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial. Modifies the \code{body} element.}
 
-\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to serif. Modifies the \code{body} element.}
+\item{text_font_base}{Body Text Base Font (Total Failure Fallback). Defaults to sans-serif. Modifies the \code{body} element.}
 
 \item{header_font_google}{Use \code{google_font()} to specify header font. Defaults to \code{NULL}. Modifies the \code{body} element.}
 
 
 \item{code_font_url}{Code Font URL. Defaults to https://fonts.googleapis.com/css?family=Source+Code+Pro:400,700&display=swap. Modifies the \verb{@import url} elements.}
 
-\item{code_font_family_fallback}{Code Font Fallback. Defaults to 'Lucida Console', Monaco. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
+\item{code_font_family_fallback}{Code Font Fallback. Defaults to Menlo, Consolas, Monaco, Liberation Mono, Lucida Console. Modifies the \verb{.remark-code, .remark-inline-code} classes.}
 
 \item{colors}{A named vector of custom colors. The names of the colors
 become CSS variables and classes that can be used within your slides.

tests/testthat/css/duo-header_bg.css

   /* Fonts */
   --text-font-family: 'Noto Serif';
   --text-font-is-google: 1;
-  --text-font-family-fallback: 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC';
-  --text-font-base: serif;
+  --text-font-family-fallback: -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial;
+  --text-font-base: sans-serif;
   --header-font-family: Cabin;
   --header-font-is-google: 1;
   --code-font-family: 'Source Code Pro';
   font-size: var(--header-h3-font-size);
 }
 .remark-code, .remark-inline-code {
-  font-family: var(--code-font-family), 'Lucida Console', Monaco, monospace;
+  font-family: var(--code-font-family), Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
 }
 .remark-code {
   font-size: var(--code-font-size);

tests/testthat/css/duo.css

   /* Fonts */
   --text-font-family: 'Noto Serif';
   --text-font-is-google: 1;
-  --text-font-family-fallback: 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC';
-  --text-font-base: serif;
+  --text-font-family-fallback: -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial;
+  --text-font-base: sans-serif;
   --header-font-family: Cabin;
   --header-font-is-google: 1;
   --code-font-family: 'Source Code Pro';
   font-size: var(--header-h3-font-size);
 }
 .remark-code, .remark-inline-code {
-  font-family: var(--code-font-family), 'Lucida Console', Monaco, monospace;
+  font-family: var(--code-font-family), Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
 }
 .remark-code {
   font-size: var(--code-font-size);

tests/testthat/css/duo_accent.css

   /* Fonts */
   --text-font-family: 'Noto Serif';
   --text-font-is-google: 1;
-  --text-font-family-fallback: 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC';
-  --text-font-base: serif;
+  --text-font-family-fallback: -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial;
+  --text-font-base: sans-serif;
   --header-font-family: Cabin;
   --header-font-is-google: 1;
   --code-font-family: 'Source Code Pro';
   font-size: var(--header-h3-font-size);
 }
 .remark-code, .remark-inline-code {
-  font-family: var(--code-font-family), 'Lucida Console', Monaco, monospace;
+  font-family: var(--code-font-family), Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
 }
 .remark-code {
   font-size: var(--code-font-size);

tests/testthat/css/duo_accent_inverse.css

   /* Fonts */
   --text-font-family: 'Noto Serif';
   --text-font-is-google: 1;
-  --text-font-family-fallback: 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC';
-  --text-font-base: serif;
+  --text-font-family-fallback: -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial;
+  --text-font-base: sans-serif;
   --header-font-family: Cabin;
   --header-font-is-google: 1;
   --code-font-family: 'Source Code Pro';
   font-size: var(--header-h3-font-size);
 }
 .remark-code, .remark-inline-code {
-  font-family: var(--code-font-family), 'Lucida Console', Monaco, monospace;
+  font-family: var(--code-font-family), Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
 }
 .remark-code {
   font-size: var(--code-font-size);

tests/testthat/css/mono_accent.css

   /* Fonts */
   --text-font-family: 'Noto Serif';
   --text-font-is-google: 1;
-  --text-font-family-fallback: 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC';
-  --text-font-base: serif;
+  --text-font-family-fallback: -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial;
+  --text-font-base: sans-serif;
   --header-font-family: Cabin;
   --header-font-is-google: 1;
   --code-font-family: 'Source Code Pro';
   font-size: var(--header-h3-font-size);
 }
 .remark-code, .remark-inline-code {
-  font-family: var(--code-font-family), 'Lucida Console', Monaco, monospace;
+  font-family: var(--code-font-family), Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
 }
 .remark-code {
   font-size: var(--code-font-size);

tests/testthat/css/mono_accent_inverse.css

   /* Fonts */
   --text-font-family: 'Noto Serif';
   --text-font-is-google: 1;
-  --text-font-family-fallback: 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC';
-  --text-font-base: serif;
+  --text-font-family-fallback: -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial;
+  --text-font-base: sans-serif;
   --header-font-family: Cabin;
   --header-font-is-google: 1;
   --code-font-family: 'Source Code Pro';
   font-size: var(--header-h3-font-size);
 }
 .remark-code, .remark-inline-code {
-  font-family: var(--code-font-family), 'Lucida Console', Monaco, monospace;
+  font-family: var(--code-font-family), Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
 }
 .remark-code {
   font-size: var(--code-font-size);

tests/testthat/css/mono_dark.css

   /* Fonts */
   --text-font-family: 'Noto Serif';
   --text-font-is-google: 1;
-  --text-font-family-fallback: 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC';
-  --text-font-base: serif;
+  --text-font-family-fallback: -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial;
+  --text-font-base: sans-serif;
   --header-font-family: Cabin;
   --header-font-is-google: 1;
   --code-font-family: 'Source Code Pro';
   font-size: var(--header-h3-font-size);
 }
 .remark-code, .remark-inline-code {
-  font-family: var(--code-font-family), 'Lucida Console', Monaco, monospace;
+  font-family: var(--code-font-family), Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
 }
 .remark-code {
   font-size: var(--code-font-size);

tests/testthat/css/mono_light-header_bg.css

   /* Fonts */
   --text-font-family: 'Noto Serif';
   --text-font-is-google: 1;
-  --text-font-family-fallback: 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC';
-  --text-font-base: serif;
+  --text-font-family-fallback: -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial;
+  --text-font-base: sans-serif;
   --header-font-family: Cabin;
   --header-font-is-google: 1;
   --code-font-family: 'Source Code Pro';
   font-size: var(--header-h3-font-size);
 }
 .remark-code, .remark-inline-code {
-  font-family: var(--code-font-family), 'Lucida Console', Monaco, monospace;
+  font-family: var(--code-font-family), Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
 }
 .remark-code {
   font-size: var(--code-font-size);

tests/testthat/css/mono_light.css

   /* Fonts */
   --text-font-family: 'Noto Serif';
   --text-font-is-google: 1;
-  --text-font-family-fallback: 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC';
-  --text-font-base: serif;
+  --text-font-family-fallback: -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial;
+  --text-font-base: sans-serif;
   --header-font-family: Cabin;
   --header-font-is-google: 1;
   --code-font-family: 'Source Code Pro';
   font-size: var(--header-h3-font-size);
 }
 .remark-code, .remark-inline-code {
-  font-family: var(--code-font-family), 'Lucida Console', Monaco, monospace;
+  font-family: var(--code-font-family), Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
 }
 .remark-code {
   font-size: var(--code-font-size);

tests/testthat/css/solarized_dark-header_bg.css

   /* Fonts */
   --text-font-family: 'Noto Serif';
   --text-font-is-google: 1;
-  --text-font-family-fallback: 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC';
-  --text-font-base: serif;
+  --text-font-family-fallback: -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial;
+  --text-font-base: sans-serif;
   --header-font-family: Cabin;
   --header-font-is-google: 1;
   --code-font-family: 'Source Code Pro';
   font-size: var(--header-h3-font-size);
 }
 .remark-code, .remark-inline-code {
-  font-family: var(--code-font-family), 'Lucida Console', Monaco, monospace;
+  font-family: var(--code-font-family), Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
 }
 .remark-code {
   font-size: var(--code-font-size);

tests/testthat/css/solarized_dark.css

   /* Fonts */
   --text-font-family: 'Noto Serif';
   --text-font-is-google: 1;
-  --text-font-family-fallback: 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC';
-  --text-font-base: serif;
+  --text-font-family-fallback: -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial;
+  --text-font-base: sans-serif;
   --header-font-family: Cabin;
   --header-font-is-google: 1;
   --code-font-family: 'Source Code Pro';
   font-size: var(--header-h3-font-size);
 }
 .remark-code, .remark-inline-code {
-  font-family: var(--code-font-family), 'Lucida Console', Monaco, monospace;
+  font-family: var(--code-font-family), Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
 }
 .remark-code {
   font-size: var(--code-font-size);

tests/testthat/css/solarized_light.css

   /* Fonts */
   --text-font-family: 'Noto Serif';
   --text-font-is-google: 1;
-  --text-font-family-fallback: 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC';
-  --text-font-base: serif;
+  --text-font-family-fallback: -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial;
+  --text-font-base: sans-serif;
   --header-font-family: Cabin;
   --header-font-is-google: 1;
   --code-font-family: 'Source Code Pro';
   font-size: var(--header-h3-font-size);
 }
 .remark-code, .remark-inline-code {
-  font-family: var(--code-font-family), 'Lucida Console', Monaco, monospace;
+  font-family: var(--code-font-family), Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
 }
 .remark-code {
   font-size: var(--code-font-size);

tests/testthat/css/xaringan.css

   /* Fonts */
   --text-font-family: 'Noto Serif';
   --text-font-is-google: 1;
-  --text-font-family-fallback: 'Palatino Linotype', 'Book Antiqua', Palatino, 'Microsoft YaHei', 'Songti SC';
-  --text-font-base: serif;
+  --text-font-family-fallback: -apple-system, BlinkMacSystemFont, avenir next, avenir, helvetica neue, helvetica, Ubuntu, roboto, noto, segoe ui, arial;
+  --text-font-base: sans-serif;
   --header-font-family: Cabin;
   --header-font-is-google: 1;
   --code-font-family: 'Source Code Pro';
   font-size: var(--header-h3-font-size);
 }
 .remark-code, .remark-inline-code {
-  font-family: var(--code-font-family), 'Lucida Console', Monaco, monospace;
+  font-family: var(--code-font-family), Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
 }
 .remark-code {
   font-size: var(--code-font-size);