Improve mobile navbar logo spacing and size

- Add margin between hamburger and logo brand
- Add margin between logo icon and text
- Increase title font to 1.25rem for better visual balance
- Add comment explaining 13px exception for mobile

Author: claude

src/css/custom.css

@@ -1176,17 +1176,26 @@ html body > div:first-child {
     padding: 4px 0;
   }
 
-  /* Improve mobile navbar - make logo bigger */
+  /*
+   * Mobile navbar branding - make logo more prominent
+   * Exception to the 13px base font: on mobile, controls are larger
+   * so we increase the logo/title to maintain visual balance
+   */
   .navbar__logo {
     width: 40px !important;
     height: 40px !important;
+    margin-right: 0.5rem !important;
+  }
+
+  .navbar__brand {
+    margin-left: 0.5rem !important;
   }
 
   .navbar .navbar__title,
   .navbar__brand .navbar__title,
   .navbar__inner .navbar__brand .navbar__title {
-    font-size: 1.1rem !important;
-    line-height: 1.4rem !important;
+    font-size: 1.25rem !important;
+    line-height: 1.5rem !important;
   }
 
   /* Better mobile bot interface */