Simplifies custom 'CSS' styling of both 'shiny' and 'rmarkdown' via 'Bootstrap' 'Sass'. Supports 'Bootstrap' 3, 4 and 5 as well as their various 'Bootswatch' themes. An interactive widget is also provided for previewing themes in real time.

The bslib R package provides a modern UI toolkit for
Shiny and R
Markdown based on
Bootstrap. It facilitates:
Install the bslib package from CRAN as follows:
install.packages("bslib")
The quickest way to see what {bslib} can do is to run
bslib::bs_theme_preview() at the console. This launches a demo app
containing both {bslib} and {shiny} UI components as well as an
theming widget (bslib::bs_themer()) overlaid on the app. See
real-time
theming
to learn more.
Since {bslib} covers a wide array of uses, it has numerous getting
started articles, each focusing on a particular interest:
There are two main places to get help with bslib:
The RStudio community is a friendly place
to ask any questions (be sure to add a bslib tag when creating a
topic).
Stack Overflow is
a great source of answers to common bslib questions. It is also a
great place to get help, once you have created a reproducible example
that illustrates your problem. Use the tags
[r][bslib] if
you ask a question. Add the tag [bslib] if you are using a Shiny
runtime.
Please note that the bslib project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.