Dark Mode Toggle
One-shot dark mode toggle: CSS variables driven by data-theme attribute, prefers-color-scheme fallback, and localStorage persistence. No flash of wrong theme on reload.
$ aoe install @impeccable/template-dark-mode-toggleProjection
Always in _index.xml · the agent never has to ask for this.
DarkModeToggle [template] v1.0.0
One-shot dark mode toggle: CSS variables driven by data-theme attribute, prefers-color-scheme fallback, and localStorage persistence. No flash of wrong theme on reload.
Loaded when retrieval picks the atom as adjacent / supporting.
DarkModeToggle [template] v1.0.0
One-shot dark mode toggle: CSS variables driven by data-theme attribute, prefers-color-scheme fallback, and localStorage persistence. No flash of wrong theme on reload.
Language
html-css-js
Meta
- License: Apache-2.0
- License Provenance: package-authorship-claim
Body
<!-- 1. Inline this in <head> BEFORE first paint to avoid flash -->
<script>
(function() {
var saved = localStorage.getItem('{STORAGE_KEY}');
var prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
var theme = saved || (prefersDark ? 'dark' : 'light');
document.documentElement.setAttribute('data-theme', theme);
})();
</script>
<!-- 2. Theme tokens (light = default, dark = override) -->
<style>
:root {
--bg: oklch(98% 0.01 250);
--fg: oklch(20% 0.02 250);
--surface: oklch(96% 0.015 250);
--border: oklch(88% 0.02 250);
--accent: oklch(60% 0.15 250);
}
:root[data-theme="dark"] {
--bg: oklch(15% 0.02 250);
--fg: oklch(95% 0.01 250);
--surface: oklch(22% 0.025 250);
--border: oklch(32% 0.03 250);
--accent: oklch(72% 0.15 250);
}
body { background: var(--bg); color: var(--fg); transition: background 200ms, color 200ms; }
@media (prefers-reduced-motion: reduce) {
body { transition: none; }
}
.theme-toggle {
background: var(--surface);
color: var(--fg);
border: 1px solid var(--border);
border-radius: 8px;
padding: 8px 12px;
cursor: pointer;
font: inherit;
}
.theme-toggle:focus-visible {
outline: 2px solid var(--accent);
outline-offset: 2px;
}
.theme-toggle .icon-dark { display: none; }
:root[data-theme="dark"] .theme-toggle .icon-light { display: none; }
:root[data-theme="dark"] .theme-toggle .icon-dark { display: inline; }
</style>
<!-- 3. The button -->
<button type="button"
class="theme-toggle"
aria-label="{TOGGLE_LABEL}"
aria-pressed="false"
data-theme-toggle>
<span class="icon-light" aria-hidden="true">{ICON_LIGHT}</span>
<span class="icon-dark" aria-hidden="true">{ICON_DARK}</span>
</button>
<!-- 4. Toggle behavior -->
<script>
(function() {
var btn = document.querySelector('[data-theme-toggle]');
if (!btn) return;
var root = document.documentElement;
function sync() {
btn.setAttribute('aria-pressed', root.getAttribute('data-theme') === 'dark' ? 'true' : 'false');
}
sync();
btn.addEventListener('click', function() {
var next = root.getAttribute('data-theme') === 'dark' ? 'light' : 'dark';
root.setAttribute('data-theme', next);
localStorage.setItem('{STORAGE_KEY}', next);
sync();
});
})();
</script>
Usage Notes
- Inline the first