Not only does bs_theme() make it easy to control Main Colors & Fonts, but it also provides access to 100s of more specific theming options. These options, sometimes referred to as Bootstrap Sass variables, allow for control over default styles of various Bootstrap features like Navs (e.g., shiny::tabsetPanel()), Navbars (e.g., shiny::navbarPage()), Dropdowns (e.g., shiny::navbarMenu()), and much more.

The table below provides a convenient way to navigate Bootstrap 4 Sass variables. A few things to keep in mind when using this table:

  1. Towards the top of the table are more general theming options like white, gray-*, black, primary, border-radius, and so on, which end up impacting more specific theming variables like btn-border-radius.
  2. bs_theme()’s bg and fg arguments provide a more convenient way to set the white, gray-*, and black variables, so there is no need to set these Sass variables directly (same goes for font_base -> $font-family-base, font_heading -> $font-family-base, and font_code -> $font-family-monospace).
  3. For Sass variables whose value defaults to another Sass variable (e.g., border-color), you may hover over the value to get the (default) CSS value that it represents.

For more information and examples on why and how to use these Sass variables inside of bs_theme(), see the theming variables section of the Custom Theming article.