Plugins may provide following global CSS variables as a style module:
--primary-text-color
--header-background-color
--footer-background-color
Plugin must be imported as .html plugin.
Complete working example:
``` html
<dom-module id="my-plugin">
<script>
Gerrit.install(function(plugin) {
plugin.registerStyleModule('app-theme', 'myplugin-app-theme');
});
</script>
</dom-module>
<dom-module id="myplugin-app-theme">
<style>
html {
--primary-text-color: #F00BAA;
--header-background-color: #F01BAA;
--footer-background-color: #F02BAA;
}
</style>
</dom-module>
```
Feature: Issue 4026
Change-Id: Ide5efa71a2da71827848c22d44219338e34edc3c