update theme to match new site

docs/_static/js/zoitechat-docs.js

@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+(() => {
+    'use strict';
+
+    const initialise = () => {
+        const picker = document.getElementById('theme-picker');
+        const preference = window.matchMedia('(prefers-color-scheme: dark)');
+
+        if (picker instanceof HTMLSelectElement) {
+            const applyTheme = () => {
+                const dark = picker.value === 'dark'
+                    || (picker.value === 'system' && preference.matches);
+                document.documentElement.dataset.theme = dark ? 'dark' : 'light';
+                document.querySelectorAll('meta[name="theme-color"]').forEach((meta) => {
+                    meta.setAttribute('content', dark ? '#111416' : '#ffffff');
+                });
+            };
+
+            // Follow the OS on every visit, including browser back/forward navigation.
+            const resetTheme = () => {
+                picker.value = 'system';
+                applyTheme();
+            };
+            picker.addEventListener('change', applyTheme);
+            preference.addEventListener('change', applyTheme);
+            window.addEventListener('pageshow', resetTheme);
+            resetTheme();
+        }
+
+        const navigation = document.getElementById('docs-navigation');
+        const compact = window.matchMedia('(max-width: 760px)');
+        if (navigation instanceof HTMLDetailsElement) {
+            const fitNavigation = () => { navigation.open = !compact.matches; };
+            compact.addEventListener('change', fitNavigation);
+            fitNavigation();
+        }
+    };
+
+    if (document.readyState === 'loading') {
+        document.addEventListener('DOMContentLoaded', initialise, { once: true });
+    } else {
+        initialise();
+    }
+})();