/* U-H: 3D viewport */
html, body, #room3d { margin: 0; padding: 0; width: 100vw; height: 100vh; overflow: hidden; }
#room3d { display: block; }
/* D-3D-2: edit-mode toolbar */
#r3-toolbar { position: fixed; top: 10px; left: 12px; z-index: 10; display: flex; gap: 8px;
  align-items: center; background: rgba(13, 17, 23, 0.88); border: 1px solid #2d3748;
  border-radius: 8px; padding: 6px 10px; color: #8b949e; font: 12px ui-monospace, Consolas, monospace; }
#r3-toolbar button { background: #2f81f7; border: none; color: #fff; border-radius: 6px;
  padding: 5px 12px; cursor: pointer; font: inherit; }
#r3-toolbar button:disabled { opacity: 0.45; cursor: default; }
#r3-toolbar button.on { background: #3fb950; }
#r3-toolbar #r3-status { color: #8b949e; }