diff --git a/src/main/mesh.js b/src/main/mesh.js
index da231b44..4be11664 100644
--- a/src/main/mesh.js
+++ b/src/main/mesh.js
@@ -166,6 +166,11 @@ function init() {
     // read from regardless of how config arrived.
     const cmmsParams = new URLSearchParams(location.search);
     const cmmsLoadUrl = cmmsParams.get('cmms_load');
+    // CMMS light/dark: cmms_dark=1|0 from theme_is_dark() (public/mesh-edit.php).
+    // Absent for non-CMMS use -> undefined -> boot defaults to dark (below), so
+    // the freestanding app keeps today's look.
+    const cmmsDarkParam = cmmsParams.get('cmms_dark');
+    const cmmsDark = cmmsDarkParam === null ? undefined : cmmsDarkParam === '1';
     if (cmmsLoadUrl) {
         self.MESH_TOOL_CONFIG = {
             loadUrl: cmmsLoadUrl,
@@ -173,9 +178,11 @@ function init() {
             ownerToken: cmmsParams.get('cmms_owner'),
             csrfToken: cmmsParams.get('cmms_csrf'),
             originalName: cmmsParams.get('cmms_name'),
+            dark: cmmsDark,
         };
         motoClient.on('ready', () => cmms_load_from_url(self.MESH_TOOL_CONFIG));
     } else {
+        self.MESH_TOOL_CONFIG = { dark: cmmsDark };
         // reload stored space when worker is ready
         motoClient.on('ready', restore_space);
     }
@@ -263,7 +270,8 @@ async function restore_workspace_from_state(cached = {}, mcache = {}) {
             let sklist = api.sketch.list().filter(s => selist.contains(s.id));
             api.selection.set([...smodel, ...sgroup, ...sklist], [...tmodel, ...tgroup]);
             api.mode[mode]();
-            set_darkmode();
+            let bootDark = (self.MESH_TOOL_CONFIG || {}).dark;
+            set_darkmode(bootDark === undefined ? true : bootDark);
         });
     });
 }
@@ -968,22 +976,34 @@ function object_destroy(id) {
 }
 
 // listen for changes like dark mode toggle
+// CMMS patch: upstream 913977ec hard-wired this to dark (deleting the light
+// branch). Restored from 913977ec^ so the Mesh:Tool follows the CMMS light/dark
+// theme (boot arg from MESH_TOOL_CONFIG.dark, default dark for non-CMMS use).
 function set_darkmode(dark) {
     let { prefs, model } = api;
     let { sky, platform } = space;
-    dark = true;
-    prefs.map.space.dark = true;
-    materials.wireframe.color.set(0xaaaaaa);
-    materials.wireline.color.set(0xaaaaaa);
+    prefs.map.space.dark = dark;
+    if (dark) {
+        materials.wireframe.color.set(0xaaaaaa);
+        materials.wireline.color.set(0xaaaaaa);
+        $('app')?.classList.add('dark');
+    } else {
+        materials.wireframe.color.set(0, 0, 0);
+        materials.wireline.color.set(0, 0, 0);
+        $('app')?.classList.remove('dark');
+    }
     sky.set({
-        color: 0,
-        ambient: { intensity: 0.55 }
+        color: dark ? 0 : 0xffffff,
+        ambient: { intensity: dark ? 0.55 : 1.1 }
     });
     platform.set({
         light: 0.08,
-        grid: {
+        grid: dark ? {
             colorMajor: 0x666666,
             colorMinor: 0x333333,
+        } : {
+            colorMajor: 0xcccccc,
+            colorMinor: 0xeeeeee,
         },
     });
     api.updateFog();
diff --git a/web/mesh/index.css b/web/mesh/index.css
index 29a85e2d..a23ed2a9 100644
--- a/web/mesh/index.css
+++ b/web/mesh/index.css
@@ -925,3 +925,30 @@ button:hover {
 @keyframes spin {
   to { transform: rotate(360deg) }
 }
+
+/* CMMS patch (not upstream): commit 913977ec made this stylesheet dark-only -
+   it baked the dark palette into the base rules and deleted every .dark
+   selector. The 3D scene follows the CMMS light/dark theme via set_darkmode()
+   (src/main/mesh.js); this re-lights the surrounding chrome when the CMMS
+   theme is light, keyed on #app NOT carrying the .dark class set_darkmode()
+   toggles. Additive and scoped - the freestanding app is always dark, so
+   #app:not(.dark) never matches there. Not exhaustive - transient surfaces
+   (boot curtain, spinner) stay dark. */
+#app:not(.dark) {
+    --accent: #2563eb;
+    --menu-blue: #2563eb;
+    --menu-back: rgba(248,250,252,0.97);
+    --border: #cbd5e1;
+    background: #f1f5f9;
+    color: #1e293b;
+}
+#app:not(.dark) #container { background: #f1f5f9; }
+#app:not(.dark) #top { color: #1e293b; }
+#app:not(.dark) #top-doc-name { border-color: #cbd5e1; background-color: #e2e8f0; }
+#app:not(.dark) #top-doc-name:hover { background-color: rgba(0,0,0,0.08); }
+#app:not(.dark) #modal_frame { background-color: rgba(248,250,252,0.97); color: #1e293b; }
+#app:not(.dark) #modal_title { color: #1e293b; background-color: rgba(226,232,240,0.9); }
+#app:not(.dark) #modal_title_close { color: #64748b; }
+#app:not(.dark) #modal_title_close:hover { color: #1e293b; }
+#app:not(.dark) .menu-items > div:hover { color: #1e293b; }
+#app:not(.dark) #logger { color: #334155; }