body { font-family: system-ui, sans-serif; margin: 16px; color: #111; background: #fff; }
nav button { margin-right: 8px; padding: 6px 12px; }
#custody-frame { display: block; width: 100%; height: 420px; border: 1px solid #ccc; margin-top: 16px; }
#app { margin-top: 12px; }
#history-list { list-style: none; padding: 0; }