@media (max-width: 850px) {
  html, body { overflow-x: hidden; }
  .app-shell, .topbar, .workspace, .editor-area, .result-panel { max-width: 100vw; }
  .topbar { grid-template-columns: minmax(0, 1fr) auto; padding: 0 10px; }
  .brand { font-size: 18px; }
  .primary-btn { padding: 0 9px; font-size: 11px; }
  .editor-area { overflow: hidden; }
  .stage-wrap { grid-template-columns: 78px minmax(0, 1fr); }
  .thumb-rail { padding-left: 6px; padding-right: 6px; }
  .editor-toolbar { padding-left: 78px; gap: 2px; overflow: hidden; }
  .tool { width: 48px; }
  .tool.compact, .tool-divider { display: none; }
}