Add client-side blog theme switcher (dropdown, localStorage, default Tokyo Night)

README.md

@@ -94,6 +94,7 @@ pointing the `shareCss` relation at the matching note – see
 | `lib/highlight.js` | vendored highlight.js | code, `application/javascript` |
 | `lib/3d/*` | three.js + OrbitControls + STLLoader + occt-wasm (OCCT V8 bundle + WASM) for the 3D viewer | code / file |
 | `lib/hljs_line_numbers.js` | highlight.js line-numbers plugin | code |
+| `scripts/blog_theme_picker.js` | theme switcher dropdown in the header (client-side, localStorage, default Tokyo Night) | code, `text/html` |
 | `scripts/*.js` | frontend share snippets (content is pasted **verbatim** into a code note, including the `<script>`/`<style>` wrapper) | code |
 | `app/3d-model-viewer-app.jsx` | JSX widget that renders the 3D viewer for model file notes inside the Trilium app (label `#widget=3dModelViewer`) | code, `text/jsx` |
 | `app/3d-worker.js` | Web Worker (STEP parsing) loaded by the app widget from a code note (CSP-safe) | code, `text/javascript` |

scripts/blog_theme_picker.js

@@ -0,0 +1,86 @@
+<style>
+.blog-theme-picker-wrap { display: inline-flex; align-items: center; gap: 6px; margin-right: 10px; flex-shrink: 0; }
+.blog-theme-picker-label { font-size: 0.78em; color: var(--text-menu); }
+.blog-theme-picker {
+    font-size: 0.8em;
+    color: var(--text-heading);
+    background: var(--background-secondary);
+    border: 1px solid var(--background-highlight);
+    border-radius: 6px;
+    padding: 3px 8px;
+    max-width: 130px;
+    cursor: pointer;
+}
+</style>
+<script>
+(function () {
+    // Replace the __THEME_*_ID__ placeholders with the note IDs of your theme notes
+    // (code notes, mime text/css, living under the .blog system note).
+    var THEMES = [
+        { id: "tokyonight", name: "Tokyo Night", url: "api/notes/__THEME_TOKYO_ID__/download" },
+        { id: "solarized", name: "Solarized", url: "api/notes/__THEME_SOLARIZED_ID__/download" },
+        { id: "coffee", name: "Coffee", url: "api/notes/__THEME_COFFEE_ID__/download" },
+        { id: "harbor", name: "Harbor", url: "api/notes/__THEME_HARBOR_ID__/download" },
+        { id: "gruvbox", name: "Gruvbox", url: "api/notes/__THEME_GRUVBOX_ID__/download" }
+    ];
+    var KEY = "blogTheme";
+    var DEFAULT = "tokyonight";
+    var currentLink = null;
+
+    function chosen() {
+        var v = null;
+        try { v = localStorage.getItem(KEY); } catch (e) {}
+        for (var i = 0; i < THEMES.length; i++) if (THEMES[i].id === v) return v;
+        return DEFAULT;
+    }
+
+    function applyTheme(id) {
+        var t = null;
+        for (var i = 0; i < THEMES.length; i++) if (THEMES[i].id === id) t = THEMES[i];
+        if (!t) return;
+        if (currentLink) {
+            try { currentLink.parentNode && currentLink.parentNode.removeChild(currentLink); } catch (e) {}
+            currentLink = null;
+        }
+        var link = document.createElement("link");
+        link.rel = "stylesheet";
+        link.href = t.url;
+        document.head.appendChild(link);
+        currentLink = link;
+    }
+
+    function build() {
+        var host = document.querySelector("#site-header");
+        if (!host) return;
+        var wrap = document.createElement("div");
+        wrap.className = "blog-theme-picker-wrap";
+        var label = document.createElement("span");
+        label.className = "blog-theme-picker-label";
+        label.textContent = "Theme";
+        var select = document.createElement("select");
+        select.className = "blog-theme-picker";
+        select.setAttribute("aria-label", "Theme");
+        THEMES.forEach(function (t) {
+            var opt = document.createElement("option");
+            opt.value = t.id;
+            opt.textContent = t.name;
+            select.appendChild(opt);
+        });
+        select.value = chosen();
+        select.addEventListener("change", function () {
+            try { localStorage.setItem(KEY, select.value); } catch (e) {}
+            applyTheme(select.value);
+        });
+        wrap.appendChild(label);
+        wrap.appendChild(select);
+        host.appendChild(wrap);
+    }
+
+    applyTheme(chosen());
+    if (document.readyState === "loading") {
+        document.addEventListener("DOMContentLoaded", build);
+    } else {
+        build();
+    }
+})();
+</script>