ThemeToggle

1 variant. Open one in isolation: use the link on each card.
Default

---
/**
 * Light/dark theme toggle button. Self-contained: reads/writes
 * `localStorage['theme']`, toggles the `.dark` class on `<html>`, and syncs the
 * `data-theme` attribute used by Expressive Code.
 *
 * Uses `data-theme-toggle` (not a fixed `id`) so multiple instances work on UI
 * gallery pages: `Base` already renders one in `SiteHeader`, and the story
 * renders another inside the preview card.
 */
interface Props {
  class?: string
}

const { class: className } = Astro.props
---

<button
  type="button"
  data-theme-toggle
  aria-label="Toggle dark mode"
  class:list={['cursor-pointer text-ink-muted bg-transparent border-0 p-0 leading-none', className]}
>
  <!-- Sun icon: shown when in dark mode, click to go light -->
  <svg class="hidden dark:block" xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
    <circle cx="12" cy="12" r="5"></circle>
    <line x1="12" y1="1" x2="12" y2="3"></line>
    <line x1="12" y1="21" x2="12" y2="23"></line>
    <line x1="4.22" y1="4.22" x2="5.64" y2="5.64"></line>
    <line x1="18.36" y1="18.36" x2="19.78" y2="19.78"></line>
    <line x1="1" y1="12" x2="3" y2="12"></line>
    <line x1="21" y1="12" x2="23" y2="12"></line>
    <line x1="4.22" y1="19.78" x2="5.64" y2="18.36"></line>
    <line x1="18.36" y1="5.64" x2="19.78" y2="4.22"></line>
  </svg>
  <!-- Moon icon: shown when in light mode, click to go dark -->
  <svg class="block dark:hidden" xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
    <path d="M21 12.79A9 9 0 1 1 11.21 3 7 7 0 0 0 21 12.79z"></path>
  </svg>
</button>

<script>
  function handleThemeToggleClick() {
    const isDark = document.documentElement.classList.toggle('dark')
    localStorage.setItem('theme', isDark ? 'dark' : 'light')
    document.documentElement.dataset.theme = isDark ? 'github-dark' : 'github-light'
  }

  for (const button of document.querySelectorAll('[data-theme-toggle]')) {
    button.addEventListener('click', handleThemeToggleClick)
  }

  window.matchMedia('(prefers-color-scheme: dark)').addEventListener('change', e => {
    if (!localStorage.getItem('theme')) {
      document.documentElement.classList.toggle('dark', e.matches)
      document.documentElement.dataset.theme = e.matches ? 'github-dark' : 'github-light'
    }
  })
</script>