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Creates a Bootstrap theme object, where you can:

  • Choose a (major) Bootstrap version.

  • Choose a Bootswatch theme (optional).

  • Customize main colors and fonts via explicitly named arguments (e.g., bg, fg, primary, etc).

  • Customize other, lower-level, Bootstrap Sass variable defaults via ....

To learn more about how to implement custom themes, as well as how to use them inside Shiny and R Markdown, see here.


  version = version_default(),
  bootswatch = NULL,
  bg = NULL,
  fg = NULL,
  primary = NULL,
  secondary = NULL,
  success = NULL,
  info = NULL,
  warning = NULL,
  danger = NULL,
  base_font = NULL,
  code_font = NULL,
  heading_font = NULL,
  font_scale = NULL

  bootswatch = NULL,
  bg = NULL,
  fg = NULL,
  primary = NULL,
  secondary = NULL,
  success = NULL,
  info = NULL,
  warning = NULL,
  danger = NULL,
  base_font = NULL,
  code_font = NULL,
  heading_font = NULL,
  font_scale = NULL




The major version of Bootstrap to use (see versions() for possible values). Defaults to the currently recommended version for new projects (currently Bootstrap 5).


The name of a bootswatch theme (see bootswatch_themes() for possible values). When provided to bs_theme_update(), any previous Bootswatch theme is first removed before the new one is applied (use bootswatch = "default" to effectively remove the Bootswatch theme).


arguments passed along to bs_add_variables().


A color string for the background.


A color string for the foreground.


A color to be used for hyperlinks, to indicate primary/default actions, and to show active selection state in some Bootstrap components. Generally a bold, saturated color that contrasts with the theme's base colors.


A color for components and messages that don't need to stand out. (Not supported in Bootstrap 3.)


A color for messages that indicate an operation has succeeded. Typically green.


A color for messages that are informative but not critical. Typically a shade of blue-green.


A color for warning messages. Typically yellow.


A color for errors. Typically red.


The default typeface.


The typeface to be used for code. Be sure this is monospace!


The typeface to be used for heading elements.


A scalar multiplier to apply to the base font size. For example, a value of 1.5 scales font sizes to 150% and a value of 0.8 scales to 80%. Must be a positive number.


a bs_theme() object.


an object.


a sass::sass_bundle() (list-like) object.


Colors may be provided in any format that htmltools::parseCssColors() can understand. To control the vast majority of the ('grayscale') color defaults, specify both the fg (foreground) and bg (background) colors. The primary and secondary theme colors are also useful for accenting the main grayscale colors in things like hyperlinks, tabset panels, and buttons.


Use base_font, code_font, and heading_font to control the main typefaces. These arguments set new defaults for the relevant font-family CSS properties, but don't necessarily import the relevant font files. To both set CSS properties and import font files, consider using the various font_face() helpers.

Each *_font argument may be collection of character vectors, font_google()s, font_link()s and/or font_face()s. Note that a character vector can have:

  • A single unquoted name (e.g., "Source Sans Pro").

  • A single quoted name (e.g., "'Source Sans Pro'").

  • A comma-separated list of names w/ individual names quoted as necessary. (e.g. c("Open Sans", "'Source Sans Pro'", "'Helvetica Neue', Helvetica, sans-serif"))

Since font_google(..., local = TRUE) guarantees that the client has access to the font family, meaning it's relatively safe to specify just one font family, for instance:

bs_theme(base_font = font_google("Pacifico", local = TRUE))

However, specifying multiple "fallback" font families is recommended, especially when relying on remote and/or system fonts being available, for instance. Fallback fonts are useful not only for handling missing fonts, but also for handling a Flash of Invisible Text (FOIT) which can be quite noticeable with remote web fonts on a slow internet connection.

bs_theme(base_font = font_collection(font_google("Pacifico", local = FALSE), "Roboto", "sans-serif"))


theme <- bs_theme(
  # Controls the default grayscale palette
  bg = "#202123", fg = "#B8BCC2",
  # Controls the accent (e.g., hyperlink, button, etc) colors
  primary = "#EA80FC", secondary = "#48DAC6",
  base_font = c("Grandstander", "sans-serif"),
  code_font = c("Courier", "monospace"),
  heading_font = "'Helvetica Neue', Helvetica, sans-serif",
  # Can also add lower-level customization
  "input-border-color" = "#EA80FC"
if (interactive()) {

# Lower-level bs_add_*() functions allow you to work more
# directly with the underlying Sass code
theme <- bs_add_variables(theme, "my-class-color" = "red")
theme <- bs_add_rules(theme, ".my-class { color: $my-class-color }")