Remove unnecessary scrollbar CSS

assets/style.css

@@ -588,15 +588,8 @@ button.fab { display: none; }
     color: var(--secondary);
 }
 .thumb-label { font-size: var(--font-sm); }
-
 .empty { padding: var(--space-4); text-align: center; }
 
-/* === Scrollbars === */
-::-webkit-scrollbar { width: 6px; }
-::-webkit-scrollbar-track { background: #111; }
-::-webkit-scrollbar-thumb { background: var(--primary); }
-::-webkit-scrollbar-thumb:hover { background: var(--primary-hover); }
-
 /* === Optional Sidebar (right side) === */
 .sidebar {
     width: 14rem;
@@ -768,9 +761,6 @@ aside.sidebar:empty { display: none; }
    holding the tree's own scroll region. Mobile: not laid out inline — its
    content is surfaced through the Overlay via the stacked FABs (see
    responsive). */
-/* No right padding on the aside: the scrolling children below reach the
-   border-right so their scrollbars sit flush against the divider line (they
-   pad their own content off the scrollbar instead). */
 .tree-sidebar {
     width: var(--tree-width);
     flex-shrink: 0;
@@ -778,16 +768,12 @@ aside.sidebar:empty { display: none; }
     padding: var(--space-4) 0 var(--space-4) var(--space-4);
     border-right: var(--border-dashed);
 }
-/* The tree's scroll region: the tree overflows here. Also the node the tree FAB
-   moves into the Overlay, so font sizing lives here rather than on the aside. */
 .tree-scroll {
     flex: 1 1 auto;
     min-height: 0;
     overflow-y: auto;
     padding-right: var(--space-2);
     font-size: var(--font-sm);
-    /* Rows are click targets (navigate / toggle), not prose — suppress the
-       text-selection highlight that double/drag clicks would otherwise leave. */
     user-select: none;
 }