Mastodon-documentation/Running-Mastodon/Customizing.md

Customizing your instance

Customizing style

If you create files prefixed with custom and suffixed with .scss (e.g. app/assets/stylesheets/custom.scss, app/assets/stylesheets/custom-foo.css), the default css will be replaced by their contents.

Changing colors

If you want to customize for example the vibrant color of your mastodon instance, you can put the following code in your custom.scss file :

$color4: #d3d900; // vibrant

@import 'application';

Don't forget to recompile your assets and restart mastodon(if you didn't have a custom.scss file before) to see the changes.