:root {
    --bg: #000000;
    --panel: #0a0a0a;
    --panel-2: #141414;
    --panel-3: #1a1a1a;
    --border: #2a2a2a;
    --border-strong: #383838;
    --text: #ffffff;
    --muted: #9e9e9e;
    --laser: #ff4d4d;
    --naive: #ffcf6e;
    --correct: #4ade80;
    --accent: #ff6b35;
    --accent-soft: rgba(255, 107, 53, 0.14);
    --accent-strong: #ff8552;
    --motor: #ff6b35;
    --selected: #ffaa00;
    --topbar-h: 60px;
  }
  * { box-sizing: border-box; }
  html, body { height: 100%; }
  body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background: var(--bg);
    color: var(--text);
    overflow: hidden;
    letter-spacing: 0.01em;
  }
  #app { position: relative; width: 100vw; height: 100vh; }
  #scene { position: absolute; top: var(--topbar-h); left: 0; right: 0; bottom: 0; }
  #scene canvas { display: block; }
  #scene.select-mode canvas { cursor: crosshair; }

  /* ----- Top header bar ----- */
  #topbar {
    position: absolute; top: 0; left: 0; right: 0;
    height: var(--topbar-h);
    display: flex; align-items: center; justify-content: space-between;
    padding: 0 22px;
    background: #000;
    border-bottom: 1px solid var(--border);
    z-index: 40;
  }
  #topbar .brand { display: flex; align-items: center; gap: 18px; }
  #topbar .brand .logo { height: 34px; width: auto; display: block; }
  #topbar .brand .sep { color: var(--border-strong); font-size: 22px; font-weight: 200; }
  #topbar .brand .title {
    font-size: 12.5px; font-weight: 600; color: var(--text);
    text-transform: uppercase; letter-spacing: 0.15em;
  }
  #topbar .brand .subtitle {
    font-size: 11px; color: var(--muted); margin-left: 10px;
    text-transform: uppercase; letter-spacing: 0.12em;
  }
  #topbar .actions { display: flex; align-items: center; gap: 8px; }
  #topbar .top-btn {
    display: inline-flex; align-items: center; gap: 8px;
    background: transparent; border: 1px solid var(--border-strong);
    color: var(--text); cursor: pointer; padding: 8px 14px;
    border-radius: 6px; font-size: 11.5px; font-weight: 600;
    text-transform: uppercase; letter-spacing: 0.1em;
    transition: background 0.15s, border-color 0.15s;
  }
  #topbar .top-btn:hover { background: var(--panel-2); border-color: var(--accent); }
  #topbar .top-btn.primary { background: var(--accent); border-color: var(--accent); color: #000; }
  #topbar .top-btn.primary:hover { background: var(--accent-strong); border-color: var(--accent-strong); }
  #topbar .top-btn svg { width: 14px; height: 14px; }
  /* Dual labels: full text on desktop, short text on mobile */
  #topbar .top-btn .label-sm { display: none; }
  #topbar .top-btn .label-lg { display: inline; }
  /* Icon-only square buttons */
  #topbar .top-btn.icon-only {
    width: 38px; height: 38px; padding: 0;
    font-size: 16px; line-height: 1;
    justify-content: center;
  }
  /* Mobile-only buttons hidden on desktop */
  #topbar .mobile-only { display: none; }
  /* Canvas swallows all touch gestures (otherwise iOS Safari tries to scroll/zoom the page) */
  #scene canvas { touch-action: none; }

  /* Drag-handle pill at the top of the bottom-sheet panel (mobile only) */
  .sheet-handle { display: none; }

  /* ----- Footer ----- */
  #footer {
    position: fixed;
    left: 16px;
    bottom: 12px;
    font-size: 10.5px;
    color: var(--muted);
    opacity: 0.55;
    letter-spacing: 0.06em;
    pointer-events: none;
    z-index: 5;
    user-select: none;
  }

  /* ----- Main controls panel ----- */
  #ui {
    position: absolute;
    top: calc(var(--topbar-h) + 16px); right: 16px;
    width: 360px;
    max-height: calc(100vh - var(--topbar-h) - 32px);
    background: rgba(10, 10, 10, 0.95);
    backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
    padding: 18px 20px;
    overflow-y: auto;
    border: 1px solid var(--border);
    border-radius: 10px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.6);
    transition: transform 0.25s ease, opacity 0.25s ease;
    z-index: 10;
  }
  #ui.collapsed { transform: translateX(calc(100% + 32px)); opacity: 0; pointer-events: none; }

  #toggle {
    position: absolute;
    top: calc(var(--topbar-h) + 16px); right: 16px;
    z-index: 20;
    width: 40px; height: 40px;
    border-radius: 50%;
    background: rgba(10,10,10,0.95);
    backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
    border: 1px solid var(--border-strong);
    color: var(--text); cursor: pointer;
    display: none; align-items: center; justify-content: center;
    font-size: 18px; box-shadow: 0 4px 12px rgba(0,0,0,0.5);
  }
  #toggle:hover { border-color: var(--accent); color: var(--accent); }
  #toggle.visible { display: flex; }

  .panel-header { display: flex; align-items: flex-start; justify-content: space-between; gap: 10px; margin-bottom: 8px; }
  .collapse-btn { background: transparent; border: none; color: var(--muted); cursor: pointer; padding: 2px 6px; font-size: 18px; line-height: 1; border-radius: 4px; flex-shrink: 0; }
  .collapse-btn:hover { color: var(--accent); background: var(--panel-2); }

  @media (max-width: 720px) {
    :root { --topbar-h: 52px; }
    /* Topbar shrinks */
    #topbar { padding: 0 12px; }
    #topbar .brand { gap: 10px; }
    #topbar .brand .logo { height: 26px; }
    #topbar .brand .sep { font-size: 18px; }
    #topbar .brand .title { font-size: 10.5px; letter-spacing: 0.1em; }
    #topbar .actions { gap: 6px; }
    /* Swap to short button labels */
    #topbar .top-btn { padding: 9px 10px; font-size: 10.5px; min-height: 36px; }
    #topbar .top-btn .label-lg { display: none; }
    #topbar .top-btn .label-sm { display: inline; }
    /* Hide the verbose "Reset" + "Elevation" buttons on tight phones — the menu button covers them */
    #topbar .top-btn:not(.icon-only):not(.mobile-only) { display: none; }
    #topbar .mobile-only { display: inline-flex; }
    #topbar .top-btn.icon-only { width: 40px; height: 40px; font-size: 18px; }

    /* Bottom-sheet panel */
    #ui {
      top: auto; left: 0; right: 0; bottom: 0; width: auto;
      max-height: 65vh;
      padding: 6px 18px 22px;
      border-radius: 16px 16px 0 0;
      border-left: none; border-right: none; border-bottom: none;
      box-shadow: 0 -12px 30px rgba(0,0,0,0.6);
      padding-bottom: calc(22px + env(safe-area-inset-bottom));
    }
    #ui.collapsed { transform: translateY(calc(100% + 24px)); }

    .sheet-handle {
      display: block;
      width: 40px; height: 4px;
      background: var(--border-strong);
      border-radius: 2px;
      margin: 6px auto 12px;
    }

    /* Hamburger toggle pinned bottom-right above safe area */
    #toggle {
      top: auto; right: 16px;
      bottom: calc(16px + env(safe-area-inset-bottom));
    }

    /* Touch-friendly target sizes */
    button.btn, .seg-toggle button { min-height: 40px; }
    .mode-toggle button { min-height: 44px; font-size: 12px; }
    input[type=range] { padding: 8px 0; }

    /* Editable value chips: bigger tap target */
    .control label .val { padding: 5px 11px; font-size: 13px; }
    input.inline-edit { padding: 5px 11px; font-size: 14px; }

    /* Per-device popup floats above bottom-sheet area */
    .device-popup { bottom: calc(72px + env(safe-area-inset-bottom)); }

    /* Hide footer on mobile — bottom sheet would cover it anyway */
    #footer { display: none; }
  }
  @media (max-height: 600px) {
    #ui { max-height: calc(100vh - var(--topbar-h) - 24px); }
  }
  /* Very narrow phones */
  @media (max-width: 380px) {
    #topbar .brand .title { display: none; }
    #topbar .brand .sep { display: none; }
    #topbar .top-btn { padding: 8px 9px; font-size: 10px; }
  }

  h1 { font-size: 13px; margin: 0; letter-spacing: 0.15em; text-transform: uppercase; font-weight: 700; }
  h3 {
    font-size: 10.5px; margin: 16px 0 10px; color: var(--muted);
    text-transform: uppercase; letter-spacing: 0.14em; font-weight: 700;
    display: flex; justify-content: space-between; align-items: center;
    padding-bottom: 6px; border-bottom: 1px solid var(--border);
  }
  .sub { font-size: 12px; color: var(--muted); margin-bottom: 14px; line-height: 1.45; }

  .control { margin-bottom: 12px; }
  .control label {
    display: flex; justify-content: space-between; align-items: baseline;
    font-size: 11.5px; margin-bottom: 6px; color: var(--muted);
    text-transform: uppercase; letter-spacing: 0.08em; font-weight: 500;
  }
  .control label .val {
    color: var(--text); font-variant-numeric: tabular-nums;
    background: var(--panel-2); padding: 3px 9px; border-radius: 4px;
    font-size: 12px; text-transform: none; letter-spacing: 0; font-weight: 600;
    border: 1px solid var(--border);
  }
  .val.editable { cursor: text; user-select: none; transition: background 0.12s, color 0.12s, border-color 0.12s; }
  .val.editable:hover { background: var(--accent-soft); color: var(--accent); border-color: var(--accent); }
  .val.editable.editing { background: var(--panel-2); padding: 0; border: none; }
  input.inline-edit {
    background: var(--panel-2); border: 1px solid var(--accent); border-radius: 4px;
    color: var(--text); font: inherit; font-variant-numeric: tabular-nums;
    padding: 3px 9px; width: 88px; outline: none; text-align: right;
    -moz-appearance: textfield; font-weight: 600;
  }
  input.inline-edit::-webkit-outer-spin-button,
  input.inline-edit::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
  .control label .val.motor { color: var(--motor); border-color: rgba(255,107,53,0.35); }
  input[type=range] { width: 100%; accent-color: var(--accent); background: transparent; }

  .seg-toggle {
    display: flex; gap: 0; width: 100%;
    background: var(--panel-2); border: 1px solid var(--border);
    border-radius: 6px; overflow: hidden; margin-top: 4px;
  }
  .seg-toggle button {
    flex: 1; background: transparent; border: none;
    color: var(--muted); padding: 9px 10px; cursor: pointer;
    font-size: 11px; font-weight: 600;
    text-transform: uppercase; letter-spacing: 0.08em;
    transition: background 0.15s, color 0.15s;
  }
  .seg-toggle button:hover { color: var(--text); background: var(--panel-3); }
  .seg-toggle button.active { background: var(--accent); color: #000; }

  .mode-toggle button { padding: 11px 12px; font-size: 11.5px; }

  button.btn {
    background: var(--panel-2); color: var(--text); border: 1px solid var(--border);
    border-radius: 6px; padding: 8px 12px; cursor: pointer;
    font-size: 11px; font-weight: 600;
    text-transform: uppercase; letter-spacing: 0.08em;
    transition: background 0.15s, border-color 0.15s, color 0.15s;
  }
  button.btn:hover { background: var(--panel-3); border-color: var(--accent); color: var(--accent); }
  button.btn.primary { background: var(--accent); border-color: var(--accent); color: #000; }
  button.btn.primary:hover { background: var(--accent-strong); border-color: var(--accent-strong); color: #000; }
  button.btn.danger { color: #ff8a8a; border-color: rgba(255,138,138,0.3); }
  button.btn.danger:hover { background: rgba(255,77,77,0.12); color: #ff5a5a; border-color: #ff5a5a; }

  .btn-row { display: flex; gap: 6px; }
  .btn-row .btn { flex: 1; }

  hr { border: none; border-top: 1px solid var(--border); margin: 14px 0; }

  /* Motors section */
  .motors-toolbar {
    display: flex; align-items: center; justify-content: space-between;
    gap: 8px; margin-bottom: 10px;
  }
  .motors-toolbar .btn { padding: 5px 10px; font-size: 11.5px; }
  .link-toggle { display: inline-flex; align-items: center; gap: 6px; font-size: 12px; color: var(--text); cursor: pointer; user-select: none; }
  .link-toggle input { accent-color: var(--accent); cursor: pointer; }
  .motors-section .motor-row { margin-bottom: 8px; }
  .motors-section .motor-row label { font-size: 12px; }
  .motors-section .motor-row label .motor-tag {
    display: inline-block;
    background: var(--accent-soft);
    color: var(--motor);
    padding: 2px 8px; border-radius: 3px;
    font-size: 10px; font-weight: 700; margin-right: 8px;
    letter-spacing: 0.06em; text-transform: uppercase;
    border: 1px solid rgba(255,107,53,0.25);
  }
  .motors-section .motor-row.linked input[type=range] { opacity: 0.45; cursor: not-allowed; }
  .motors-section .motor-row.linked label .motor-tag { background: var(--panel-2); color: var(--muted); border-color: var(--border); }
  .motors-section .motor-row.linked label .val { color: var(--muted); }

  /* Plan diagram inline */
  .plan-wrap { background: var(--panel-2); border: 1px solid var(--border); border-radius: 8px; padding: 8px; }
  .plan-wrap svg { display: block; width: 100%; height: auto; }

  /* Device readings table */
  table.devices { width: 100%; border-collapse: collapse; font-size: 12px; font-variant-numeric: tabular-nums; margin-top: 6px; }
  table.devices th {
    text-align: left; color: var(--muted); font-weight: 700;
    padding: 8px 6px 8px 8px; border-bottom: 1px solid var(--border);
    font-size: 10px; text-transform: uppercase; letter-spacing: 0.1em;
  }
  table.devices td { padding: 7px 6px 7px 8px; border-bottom: 1px solid rgba(40,40,40,0.6); cursor: pointer; }
  table.devices td.hl { color: var(--correct); font-weight: 600; }
  table.devices td.idx { color: var(--muted); width: 22px; }
  table.devices tr.selected td { background: rgba(255,170,0,0.06); }
  table.devices tr.selected td.idx { color: var(--selected); }
  table.devices tr:hover td { background: rgba(255,107,53,0.06); }
  table.devices tr:last-child td { border-bottom: none; }
  .empty-table { color: var(--muted); font-size: 12px; padding: 10px 0; text-align: center; font-style: italic; }

  .legend { display: flex; align-items: center; gap: 8px; font-size: 12px; color: var(--muted); margin: 4px 0; }
  .swatch { width: 12px; height: 4px; border-radius: 2px; }
  .swatch.dot { width: 10px; height: 10px; border-radius: 50%; }
  .tip { color: var(--muted); opacity: 0.7; font-size: 11px; margin-top: 10px; line-height: 1.5; }
  .formula { font-family: "SF Mono", Menlo, Consolas, monospace; font-size: 11px; color: var(--accent); background: var(--accent-soft); padding: 5px 9px; border-radius: 4px; margin-top: 6px; display: inline-block; border: 1px solid rgba(255,107,53,0.2); }

  .plan-toolbar { display: flex; gap: 4px; }
  .icon-btn {
    background: transparent; border: 1px solid var(--border); color: var(--muted);
    width: 24px; height: 24px; border-radius: 4px; cursor: pointer;
    display: inline-flex; align-items: center; justify-content: center;
    font-size: 12px; line-height: 1;
    transition: color 0.15s, border-color 0.15s, background 0.15s;
  }
  .icon-btn:hover { color: var(--accent); background: var(--accent-soft); border-color: var(--accent); }


  /* ----- Per-device popup (fixed at bottom centre) ----- */
  .device-popup {
    position: fixed;
    left: 50%;
    bottom: 20px;
    transform: translateX(-50%);
    width: 280px;
    background: rgba(10,10,10,0.97);
    backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
    border: 1px solid var(--selected);
    border-radius: 10px;
    padding: 14px 16px;
    z-index: 50;
    box-shadow: 0 12px 40px rgba(0,0,0,0.7);
    pointer-events: auto;
  }
  .device-popup.hidden { display: none; }
  @media (max-width: 720px) {
    .device-popup { left: 12px; right: 12px; width: auto; transform: none; }
  }
  .device-popup .popup-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 10px; }
  .device-popup .popup-header strong { color: var(--selected); font-size: 13px; }
  .device-popup .control { margin-bottom: 8px; }
  .device-popup .control label { font-size: 12px; }
  .device-popup .control label .val { font-size: 11px; }
  .device-popup .popup-actions { display: flex; gap: 6px; margin-top: 10px; }
  .device-popup .popup-actions .btn { flex: 1; padding: 6px 8px; font-size: 11.5px; }