CSS Theme

A plugin is considered a theme if it aims to to change the default style of the League Client, rather than creating helpers for the Client.

Creating a theme

From your plugin entry, use import to add it:

import './theme.css'

This line will append a link tag to body pointing to theme.css next to your index.js .

your-plugin/
  |__index.js       <- plugin entry
  |__theme.css      <- your theme

Changing the default font

The following will import a custom font from Google Fonts and override the default font using the :root selector and CSS variables.

/* theme.css */
@import url('https://fonts.googleapis.com/css2?family=Shantell+Sans&display=swap');

:root {
  /* override default League font */
  --font-display: 'Shantell Sans', sans-serif !important;
  --font-body: 'Shantell Sans', sans-serif !important;
}

Note that some selectors may no be applied due to the priority, you can force them on top of the rules with the !important suffix.

To get more CSS variables used by the Client, you should inpsect them using the Chrome DevTools. Try hitting the Ctrl Shift I key to open it.

CSS module

When you import the theme, your theme becomes a module. Now you can use the relative path of url() to import assets.

/* theme.css */
.some-div {
  background-image: url(./assets/background.png);
}

.another-div {
  background-image: url(./assets/some-image.jpg);
}

The corresponding plugin structure:

your-plugin/
  |__assets/
    |__background.png
    |__some-image.jpg
  |__theme.css

Remote theme

Using remote theme keeps your theme up to date.

The following will inject a stylesheet link tag pointing to your theme from https://example.com/theme.css

// index.js
function addCssLink(url) {
  const link = document.createElement('link')
  link.href = url
  link.type = 'text/css'
  link.rel = 'stylesheet'
  document.head.appendChild(link)
}

window.addEventListener('load', () => {
  addCssLink('https://example.com/theme.css')
})

INFO

Your server should respond with MIME type text/css .