Navigation pane에서 폴더를 클릭하면, 해당 폴더가 펼쳐지면서 서브 폴더 목록을 보여주기

src/renderer/style.css

@@ -450,9 +450,12 @@ footer span { font-size: 11px; color: var(--muted); }
   display: flex; align-items: center; justify-content: center;
   flex-shrink: 0; color: var(--muted);
   transition: transform .15s;
+  cursor: pointer;
+  border-radius: 3px;
 }
+.tree-chevron:hover { background: rgba(255,255,255,.08); color: var(--text); }
 .tree-chevron.open { transform: rotate(90deg); }
-.tree-chevron svg { display: block; }
+.tree-chevron svg { display: block; pointer-events: none; }
 
 .tree-icon {
   width: 16px; height: 16px;