shoelace/docs/getting-started/themes.md

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Themes

Shoelace ships with a dark theme that complements the default light theme. You can even take things a step further by designing your own custom theme.

The default theme is included as part of themse/base.css and should always be loaded first, even if you want to use another theme exclusively. The default theme contains important base tokens and utilities that many components rely on.

Dark Mode

To install the dark theme, add the following to the <head> section of your app.

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@shoelace-style/shoelace@%VERSION%/dist/themes/dark.css">

Themes must be activated after importing! You can do this by adding the sl-theme-[name] class to the <body> element.

<body class="sl-theme-dark">
  ...
</body>

Detecting the User's Color Scheme Preference

Shoelace doesn't try to auto-detect the user's light/dark mode preference. This should be done at the application level. As a best practice, to provide a dark theme in your app, you should:

  • Check for prefers-color-scheme and use its value by default
  • Allow the user to override the setting in your app
  • Remember the user's preference and restore it on subsequent logins

Shoelace avoids using the prefers-color-scheme media query because not all apps support dark mode, and it would break things for the ones that don't.

Creating a Theme

A theme is nothing more than a stylesheet that uses the Shoelace API to customize design tokens and/or components. To create a theme, you will need a decent understanding of CSS, including CSS Custom Properties and the ::part selector.

The recommended way to create a theme is to piggyback on top of the default theme, adjusting design tokens and styling components as necessary to achieve the look you want. This makes your theme lightweight and "future proof", as upcoming versions of Shoelace may introduce new design tokens and components that your theme won't support initially. The default theme will account for these so components won't appear to be broken.

Technically, you can roll your own theme from scratch without using the default theme as a baseline, but that approach isn't recommended.

Theme Classes

All theme classes must use the sl-theme-{name} convention, where {name} is a lowercase, hyphen-delimited value representing the name of your theme. For example, a theme called "Purple Power" would use the sl-theme-purple-power class.

Every selector in a theme must be scoped to the theme's class to ensure interoperability with other themes.

Design Tokens

Design tokens give you a high-level way to customize Shoelace components. You can customize them in your theme as shown below.

.sl-theme-purple-power { 
  --sl-color-primary-50: #faf5ff;
  --sl-color-primary-100: #f3e8ff;
  --sl-color-primary-200: #e9d5ff;
  /* ... */
}

?> Avoid scoping design tokens to :root. You may notice that the default theme does this, but that's because it's not technically a theme — it's a set of design tokens and base styles that themes can use as a foundation to build upon.

Components

To customize individual components, use the following syntax. Available "parts" can be found in the CSS Parts section of each component's documentation.

.sl-theme-purple-power sl-button::part(base) {
  /* your custom button styles here */
}

?> Pay special attention to each component's CSS Parts API. You almost always need to use a ::part selector when theming components!

Using a Custom Theme

If a theme adheres to the guidelines above, you can use it by importing the stylesheet and activating it with the sl-theme-[name] class.

<head>
  ...
  <link rel="stylesheet" href="path/to/purple-power.css">
</head>

<body class="sl-theme-purple-power">
   ...
</body>

If desired, you can import and activate more than one theme on the same page.

Submitting a Theme

I am very interested in showcasing well-designed themes that complement this library. To submit a theme for review, please open an issue on GitHub with the theme linked or attached. Once approved, your theme will be showcased on this page.

Please note the following requirements before submitting a theme.

  • Themes must be complete and of high quality
  • Themes must be available under an open source license
  • Derivative works must be properly credited