ui(electron): polish toolbar

src/main/frontend/components/theme.css

@@ -95,11 +95,13 @@ html[data-theme=light] {
 html.is-electron {
   --frame-top-height: 24px;
 
-  .theme-inner {}
+  .theme-inner {
+  }
 
   .cp__header {
     height: 2rem;
     padding-top: var(--frame-top-height);
+    background-color: var(--ls-primary-background-color);
     top: 0;
   }
 
@@ -109,7 +111,8 @@ html.is-electron {
 
   &.is-mac {
     .cp__header {
-      padding-top: calc(var(--frame-top-height) + 12px);
+      height: calc(2.2rem + var(--frame-top-height));
+      padding-top: var(--frame-top-height);
 
       &-logo {
         height: var(--frame-top-height);