:root {
  --elevation-0: none;
  --elevation-1: none; /* surface lift only — background color communicates depth */
  --elevation-2: 0 0.5px 0 0 rgba(255,255,255,0.10) inset, 0 10px 30px 0 rgba(0,0,0,0.25);
  --elevation-3: 0 0 0 1px rgba(0,153,255,0.15);
  --elevation-active-outline: 0 0 0 2px rgba(0,0,0,0.9);
}