body { font-family: Arial; background:#111; color:white; text-align:center; }
input, button { padding:10px; margin:5px; font-size:16px; }
#error { color:red; }
.tree-node { background:#1e1e1e; border-radius:8px; padding:6px 8px; margin:4px; text-align:left; display:inline-block; min-width:220px; }
.plz { color:#aaa; }
.toggle { margin-right:5px; font-weight:bold; cursor:pointer; }