title: CSS variables
description: Use Bootstrap’s CSS custom properties for fast and forward-looking design and development.
toc: true
+mdn: https://developer.mozilla.org/en-US/docs/Web/CSS/Using_CSS_custom_properties
+csstricks: https://css-tricks.com/a-complete-guide-to-custom-properties/
---
Bootstrap includes many [CSS custom properties (variables)](https://developer.mozilla.org/en-US/docs/Web/CSS/Using_CSS_custom_properties) in its compiled CSS for real-time customization without the need to recompile Sass. These provide easy access to commonly used values like our theme colors, breakpoints, and primary font stacks when working in your browser’s inspector, a code sandbox, or general prototyping.
title: Flex
description: Quickly manage the layout, alignment, and sizing of grid columns, navigation, components, and more with a full suite of responsive flexbox utilities. For more complex implementations, custom CSS may be necessary.
toc: true
-mdn: https://developer.mozilla.org/en-US/docs/Web/CSS/flex
+mdn: https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/CSS_layout/Flexbox
csstricks: https://css-tricks.com/snippets/css/a-guide-to-flexbox/
---