diff --git a/src/routes/+layout.ts b/src/routes/+layout.ts
index 134f4ffd..631c1566 100644
--- a/src/routes/+layout.ts
+++ b/src/routes/+layout.ts
@@ -393,6 +393,19 @@ export async function load({ fetch, params, parent, route, url }) {
     ae_loc_init['site_google_tracking_id'] = json_data.google_tracking_id || '';
     ae_loc_init['site_access_code_kv'] = json_data.access_code_kv_json || {};
     ae_loc_init['site_cfg_json'] = json_data.cfg_json || {};
+    // If the site-level cfg_json provides a theme, apply it as a default
+    // so the site admin can select a preferred theme via site.cfg_json.
+    // This will later be overridable by a URL `?theme=` param or user/local setting.
+    try {
+        const scfg = ae_loc_init['site_cfg_json'] as any;
+        if (scfg && typeof scfg === 'object') {
+            if (scfg.theme_name) ae_loc_init['theme_name'] = scfg.theme_name;
+            if (scfg.theme_mode && (scfg.theme_mode === 'light' || scfg.theme_mode === 'dark'))
+                ae_loc_init['theme_mode'] = scfg.theme_mode;
+        }
+    } catch (e) {
+        // Defensive: if parsing fails, don't block boot.
+    }
     ae_loc_init['site_access_key'] = json_data.access_key || '';
     ae_loc_init['site_domain_access_key'] =
         json_data.site_domain_access_key || '';