Bootstrap/site/content/docs/4.3/customize/css-variables.md

---
layout: docs
title: CSS variables
description: Use Bootstrap's CSS custom properties for fast and forward-looking design and development.
group: customize
toc: true
---

Bootstrap includes around two dozen [CSS custom properties (variables)](https://developer.mozilla.org/en-US/docs/Web/CSS/Using_CSS_custom_properties) in its compiled CSS. These provide easy access to commonly used values like our theme colors and primary font stacks when working in your browser's Inspector, a code sandbox, or general prototyping.

**All our custom properties are prefixed with `bs-` to avoid conflicts with third party CSS.**

## Available variables

Here are the variables we include (note that the `:root` is required). They're located in our `_root.scss` file.

{{< highlight css >}}
{{< root.inline >}}
{{- $css := readFile "dist/css/bootstrap.css" -}}
{{- $match := findRE ":root {([^}]*)}" $css 1 -}}

{{- if (eq (len $match) 0) -}}
{{- errorf "Got no matches for :root in %q!" $.Page.Path -}}
{{- end -}}

{{- index $match 0 -}}

{{< /root.inline >}}
{{< /highlight >}}

## Examples

CSS variables offer similar flexibility to Sass's variables, but without the need for compilation before being served to the browser. For example, here we're resetting our page's font and link styles with CSS variables.

{{< highlight css >}}
body {
  font: 1rem/1.5 var(--bs-font-sans-serif);
}
a {
  color: var(--bs-blue);
}
{{< /highlight >}}