.mode-ctrl .seg button[data-mode="learn"].on {
    background: var(--accent); color: white;
  }
  .mode-ctrl .seg button[data-mode="practice"].on {
    background: oklch(0.55 0.15 140); color: white;
  }
  .mode-ctrl .seg button[data-mode="test"].on {
    background: oklch(0.58 0.16 35); color: white;
  }

  /* Learn mode: hide practice-only controls */
  body.mode-learn .practice-only { display: none !important; }
  /* Practice mode: hide learn-only elements */
  body.mode-practice .learn-only { display: none !important; }
  body:not(.mode-test) .test-only { display: none !important; }
  body:not(.learn-compare) .learn-compare-only { display: none !important; }
  body:not(.nested-raid) .nested-only { display: none !important; }
  body.mode-learn.learn-compare .board-wrap,
  body.mode-learn.learn-compare .info-section,
  body.mode-learn.learn-compare .config-control,
  body.mode-learn.learn-compare .side,
  body.mode-learn.learn-compare .side-resizer { display: none !important; }
  body.mode-learn.learn-compare main { grid-template-columns: 1fr; }
  body.mode-test .learn-only,
  body.mode-test .lesson,
  body.mode-test .info-section,
  body.mode-test .config-control,
  body.mode-test .practice-action { display: none !important; }
  body.mode-test:not(.test-build) .practice-only,
  body.mode-test:not(.test-build) .board-wrap,
  body.mode-test:not(.test-build) .side,
  body.mode-test:not(.test-build) .side-resizer { display: none !important; }
  body.mode-test:not(.test-build) main { grid-template-columns: 1fr; }
  body.mode-test .stage {
    width: min(100%, 1120px);
    justify-self: center;
  }
  body.mode-test .footer-level-shortcut { display: none; }
  body.mode-learn.learn-compare .footer-level-shortcut { display: none; }

  /* Learn mode: blocks non-interactive */
  body.mode-learn .block { pointer-events: none; cursor: default; }
  body.mode-learn .disk-head { display: none; }
  body.mode-learn .connect-bar { pointer-events: none; opacity: 0.5; }
  body:not(.nested-raid) .disk-head { display: none; }
  body.nested-raid:not(.mode-learn) .disk-check { display: grid; }
  body:not(.nested-raid) .disk-head { cursor: default; }