--- layout: default title: Custom CSS parent: Customizing nav_order: 99 permalink: /customizing/custom-css --- ## Custom-CSS The custom.css file allows you to customize the appearance of Mainsail without the need of rebuilding it. All you need to do is to place a file named "custom.css" into the configuration directory ".theme" and define your css rules in there. ![screenshot](../assets/img/customizing/screenshot-custom-css.png)