Fix CSS selector to target span inside menu-item-action

- Changed from .menu-item-action to .menu-item-action span
- Correctly applies width and text-align to the span element
- More specific targeting as intended by user

static/css/main.css

@@ -2087,7 +2087,7 @@ a:focus {
 }
 
 /* Menu item action controls (Expand All, Collapse All) */
-.menu-item-action {
+.menu-item-action span {
     width: calc(100% - 65px);
     text-align: center;
 }