Fix submenu arrow: flexbox centering, proper spacing

- Use display: flex + align-items: center on dropdown-toggle
- gap: 0.75rem between text and arrow
- Remove float: right and margin-top hack
- chevron-right: flex-shrink: 0, font-size: 0.7rem

themes/default/assets/scss/theme.scss

@@ -369,10 +369,17 @@ $header-bg-opacity: 1;
         background-color: rgba(255, 255, 255, 0.15) !important;
     }
 
-    // Arrow pointing right
-    > .dropdown-toggle .bi-chevron-right {
-        float: right;
-        margin-top: 0.25rem;
+    // Arrow pointing right — vertically centered with text
+    > .dropdown-toggle {
+        display: flex !important;
+        justify-content: space-between;
+        align-items: center;
+        gap: 0.75rem;
+
+        .bi-chevron-right {
+            flex-shrink: 0;
+            font-size: 0.7rem;
+        }
     }
 }