1 files changed, 97 insertions, 0 deletions
diff --git a/docs/src/components/ThemeToggle.tsx b/docs/src/components/ThemeToggle.tsx
new file mode 100644
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+++ b/docs/src/components/ThemeToggle.tsx
@@ -0,0 +1,97 @@
+import type { FunctionalComponent } from 'preact';
+import { h, Fragment } from 'preact';
+import { useState, useEffect } from 'preact/hooks';
+
+const themes = ['system', 'light', 'dark'];
+
+const icons = [
+  <svg
+    xmlns="http://www.w3.org/2000/svg"
+    width="20"
+    height="20"
+    viewBox="0 0 20 20"
+    fill="currentColor"
+  >
+    <path
+      fill-rule="evenodd"
+      d="M3 5a2 2 0 012-2h10a2 2 0 012 2v8a2 2 0 01-2 2h-2.22l.123.489.804.804A1 1 0 0113 18H7a1 1 0 01-.707-1.707l.804-.804L7.22 15H5a2 2 0 01-2-2V5zm5.771 7H5V5h10v7H8.771z"
+      clip-rule="evenodd"
+    />
+  </svg>,
+  <svg
+    xmlns="http://www.w3.org/2000/svg"
+    width="20"
+    height="20"
+    viewBox="0 0 20 20"
+    fill="currentColor"
+  >
+    <path
+      fillRule="evenodd"
+      d="M10 2a1 1 0 011 1v1a1 1 0 11-2 0V3a1 1 0 011-1zm4 8a4 4 0 11-8 0 4 4 0 018 0zm-.464 4.95l.707.707a1 1 0 001.414-1.414l-.707-.707a1 1 0 00-1.414 1.414zm2.12-10.607a1 1 0 010 1.414l-.706.707a1 1 0 11-1.414-1.414l.707-.707a1 1 0 011.414 0zM17 11a1 1 0 100-2h-1a1 1 0 100 2h1zm-7 4a1 1 0 011 1v1a1 1 0 11-2 0v-1a1 1 0 011-1zM5.05 6.464A1 1 0 106.465 5.05l-.708-.707a1 1 0 00-1.414 1.414l.707.707zm1.414 8.486l-.707.707a1 1 0 01-1.414-1.414l.707-.707a1 1 0 011.414 1.414zM4 11a1 1 0 100-2H3a1 1 0 000 2h1z"
+      clipRule="evenodd"
+    />
+  </svg>,
+  <svg
+    xmlns="http://www.w3.org/2000/svg"
+    width="20"
+    height="20"
+    viewBox="0 0 20 20"
+    fill="currentColor"
+  >
+    <path d="M17.293 13.293A8 8 0 016.707 2.707a8.001 8.001 0 1010.586 10.586z" />
+  </svg>,
+];
+
+const ThemeToggle: FunctionalComponent = () => {
+  const [theme, setTheme] = useState(themes[0]);
+
+  useEffect(() => {
+    const user = localStorage.getItem('theme');
+    if (!user) return;
+    setTheme(user);
+  }, []);
+
+  useEffect(() => {
+    const root = document.documentElement;
+    if (theme === 'system') {
+      localStorage.removeItem('theme');
+      if (window.matchMedia('(prefers-color-scheme: dark)').matches) {
+        root.classList.add('theme-dark');
+      } else {
+        root.classList.remove('theme-dark');
+      }
+    } else {
+      localStorage.setItem('theme', theme);
+      if (theme === 'light') {
+        root.classList.remove('theme-dark');
+      } else {
+        root.classList.add('theme-dark');
+      }
+    }
+  }, [theme]);
+
+  return (
+    <div id="theme-toggle">
+      {themes.map((t, i) => {
+        const icon = icons[i];
+        const checked = t === theme;
+        return (
+          <label className={checked ? 'checked' : ''}>
+            {icon}
+            <input
+              type="radio"
+              name="theme-toggle"
+              checked={checked}
+              value={t}
+              title={`Use ${t} theme`}
+              aria-label={`Use ${t} theme`}
+              onChange={() => setTheme(t)}
+            />
+          </label>
+        );
+      })}
+    </div>
+  );
+};
+
+export default ThemeToggle;