:root {
    --bg: #07080c;
    --bg-2: #0d1018;
    --ink: #e8ecf2;
    --ink-dim: #6b7689;
    --accent: #ff3864;
    --accent-2: #2de2e6;
    --accent-3: #f9c80e;
    --tube-stroke: rgba(232, 236, 242, 0.22);
    --tube-stroke-sel: rgba(45, 226, 230, 0.85);
    --tube-stroke-target: rgba(45, 226, 230, 0.35);

    --c-red:    #ff4d5e;
    --c-yellow: #ffd93d;
    --c-blue:   #4d8bff;
    --c-orange: #ff8b3d;
    --c-green:  #4dd56b;
    --c-purple: #b85dff;
    --c-brown:  #8a6a4a;
  }

  * { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }

  html, body {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    background: var(--bg);
    color: var(--ink);
    font-family: 'JetBrains Mono', ui-monospace, monospace;
    user-select: none;
    -webkit-user-select: none;
    overscroll-behavior: none;
    touch-action: manipulation;
  }

  #stage {
    position: fixed;
    inset: 0;
    width: 100%;
    height: 100%;
    background:
      radial-gradient(ellipse at center, #0f1320 0%, #07080c 60%, #04050a 100%);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-end;
    overflow: hidden;
  }

  /* ───── HUD ───── */
  .hud {
    position: fixed;
    top: 0; left: 0; right: 0;
    padding: 18px 18px 0;
    padding-top: max(18px, env(safe-area-inset-top));
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    pointer-events: none;
    z-index: 10;
  }

  .hud-block {
    background: rgba(7, 8, 12, 0.55);
    backdrop-filter: blur(6px);
    -webkit-backdrop-filter: blur(6px);
    border: 1px solid rgba(232, 236, 242, 0.08);
    padding: 8px 12px;
    border-radius: 2px;
    pointer-events: auto;
  }

  .label {
    font-size: 9px;
    letter-spacing: 0.22em;
    text-transform: uppercase;
    color: var(--ink-dim);
    margin-bottom: 4px;
  }

  .value {
    font-size: 18px;
    font-weight: 700;
    letter-spacing: 0.05em;
    line-height: 1;
  }
  .value.accent { color: var(--accent-2); }

  /* ───── Target panel ───── */
  .target-panel {
    position: fixed;
    top: calc(max(18px, env(safe-area-inset-top)) + 56px);
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 6px;
    pointer-events: none;
    z-index: 9;
  }
  .target-label {
    font-size: 9px;
    letter-spacing: 0.32em;
    text-transform: uppercase;
    color: var(--ink-dim);
  }
  .target-row {
    display: flex;
    gap: 6px;
    padding: 6px 10px;
    border: 1px dashed var(--tube-stroke-target);
    background: rgba(7,8,12,0.55);
    backdrop-filter: blur(6px);
    -webkit-backdrop-filter: blur(6px);
    border-radius: 2px;
  }
  .mini-tube {
    width: 14px;
    height: 36px;
    border: 1px solid var(--tube-stroke-target);
    border-top: none;
    border-radius: 0 0 6px 6px;
    background: rgba(7,8,12,0.4);
    display: flex;
    flex-direction: column-reverse;
    overflow: hidden;
  }
  .mini-layer {
    flex: 1 1 0;
  }

  /* ───── Tubes board ───── */
  .board-wrap {
    flex: 1;
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 160px 16px 120px;
    overflow: visible;
  }
  .board {
    position: relative;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    align-items: flex-end;
    gap: 18px 18px;
    width: 100%;
    max-width: 480px;
  }

  .tube {
    position: relative;
    width: 54px;
    height: 200px;
    border: 1.5px solid var(--tube-stroke);
    border-top: none;
    border-radius: 0 0 26px 26px;
    background: rgba(7, 8, 12, 0.4);
    display: flex;
    flex-direction: column-reverse;
    overflow: hidden;
    cursor: pointer;
    transition: transform 0.25s ease, border-color 0.18s ease, box-shadow 0.18s ease;
    transform-origin: 50% calc(100% - 12px);
  }
  .tube::before {
    content: '';
    position: absolute;
    top: -1.5px;
    left: -1.5px;
    right: -1.5px;
    height: 6px;
    border-top: 1.5px solid var(--tube-stroke);
    border-left: 1.5px solid var(--tube-stroke);
    border-right: 1.5px solid var(--tube-stroke);
    pointer-events: none;
  }
  .tube::after {
    content: '';
    position: absolute;
    top: 4px; bottom: 4px;
    left: 8px;
    width: 6px;
    background: linear-gradient(180deg, rgba(255,255,255,0.10), rgba(255,255,255,0));
    border-radius: 4px;
    pointer-events: none;
  }
  .tube.selected {
    transform: translateY(-12px);
    border-color: var(--tube-stroke-sel);
    box-shadow: 0 0 24px rgba(45, 226, 230, 0.25);
  }
  .tube.complete {
    border-color: rgba(77, 213, 107, 0.55);
    box-shadow: 0 0 18px rgba(77, 213, 107, 0.15);
  }
  .tube.invalid {
    animation: shake 0.32s ease;
  }
  /* during pour: source tube tilts toward destination */
  .tube.pouring-src {
    transition: transform 0.35s cubic-bezier(.5,.0,.5,1);
    z-index: 5;
  }
  .tube.pouring-dst {
    z-index: 4;
  }
  @keyframes shake {
    0%, 100% { transform: translateX(0); }
    25%      { transform: translateX(-4px); }
    75%      { transform: translateX(4px); }
  }

  .layer {
    width: 100%;
    flex: 1 1 0;
    transition: background 0.35s ease;
  }
  .layer + .layer { box-shadow: inset 0 1px 0 rgba(0,0,0,0.25); }

  /* color classes used everywhere */
  .c-red    { background: var(--c-red); }
  .c-yellow { background: var(--c-yellow); }
  .c-blue   { background: var(--c-blue); }
  .c-orange { background: var(--c-orange); }
  .c-green  { background: var(--c-green); }
  .c-purple { background: var(--c-purple); }
  .c-brown  { background: var(--c-brown); }

  /* Pour droplet (absolute, animated via JS-set CSS vars) */
  .droplet {
    position: fixed;
    width: 10px;
    height: 14px;
    border-radius: 50% 50% 40% 40% / 60% 60% 40% 40%;
    pointer-events: none;
    z-index: 50;
    transform: translate(-50%, -50%);
    box-shadow: 0 0 8px currentColor;
  }
  .droplet.c-red    { background: var(--c-red);    color: var(--c-red); }
  .droplet.c-yellow { background: var(--c-yellow); color: var(--c-yellow); }
  .droplet.c-blue   { background: var(--c-blue);   color: var(--c-blue); }
  .droplet.c-orange { background: var(--c-orange); color: var(--c-orange); }
  .droplet.c-green  { background: var(--c-green);  color: var(--c-green); }
  .droplet.c-purple { background: var(--c-purple); color: var(--c-purple); }
  .droplet.c-brown  { background: var(--c-brown);  color: var(--c-brown); }

  /* ───── Bottom controls ───── */
  .controls {
    position: fixed;
    bottom: 0; left: 0; right: 0;
    padding: 18px;
    padding-bottom: max(18px, env(safe-area-inset-bottom));
    display: flex;
    justify-content: center;
    gap: 12px;
    z-index: 10;
  }
  .icon-btn {
    background: rgba(7, 8, 12, 0.55);
    backdrop-filter: blur(6px);
    -webkit-backdrop-filter: blur(6px);
    border: 1px solid rgba(232, 236, 242, 0.12);
    color: var(--ink);
    width: 48px; height: 48px;
    display: flex; align-items: center; justify-content: center;
    cursor: pointer;
    transition: transform 0.15s ease, background 0.15s ease;
  }
  .icon-btn:active { transform: scale(0.94); background: rgba(45, 226, 230, 0.08); }
  .icon-btn svg { width: 20px; height: 20px; }
  .icon-btn[disabled] { opacity: 0.3; pointer-events: none; }

  /* ───── Overlays ───── */
  .overlay {
    position: fixed;
    inset: 0;
    background: var(--bg);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 30;
    gap: 24px;
    padding: 32px;
    text-align: center;
  }
  .overlay.hidden { display: none; }

  .title {
    font-family: 'Major Mono Display', monospace;
    font-size: 44px;
    letter-spacing: 0.08em;
    line-height: 0.95;
    color: var(--ink);
    text-shadow:
      0 0 24px rgba(45, 226, 230, 0.3),
      0 0 60px rgba(45, 226, 230, 0.15);
  }
  .subtitle {
    font-size: 11px;
    letter-spacing: 0.4em;
    text-transform: uppercase;
    color: var(--ink-dim);
    max-width: 280px;
    line-height: 1.8;
  }
  .btn {
    background: transparent;
    border: 1px solid var(--ink);
    color: var(--ink);
    font-family: 'JetBrains Mono', monospace;
    font-size: 12px;
    letter-spacing: 0.3em;
    text-transform: uppercase;
    padding: 14px 32px;
    cursor: pointer;
    font-weight: 500;
    transition: all 0.18s ease;
  }
  .btn:active {
    background: var(--ink);
    color: var(--bg);
    transform: scale(0.97);
  }
  .btn.ghost {
    border-color: var(--ink-dim);
    color: var(--ink-dim);
    font-size: 10px;
    padding: 10px 22px;
    letter-spacing: 0.25em;
  }
  .stats-line {
    font-size: 11px;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: var(--ink-dim);
  }
  .stats-line strong {
    color: var(--accent-2);
    font-weight: 700;
  }

  /* level announce */
  .level-announce {
    position: fixed;
    top: 38%;
    left: 50%;
    transform: translate(-50%, -50%);
    pointer-events: none;
    z-index: 15;
    text-align: center;
    opacity: 0;
  }
  .level-announce.show { animation: levelPop 1.4s ease forwards; }
  @keyframes levelPop {
    0%   { opacity: 0; transform: translate(-50%, -50%) scale(0.9); }
    20%  { opacity: 1; transform: translate(-50%, -50%) scale(1); }
    80%  { opacity: 1; transform: translate(-50%, -50%) scale(1); }
    100% { opacity: 0; transform: translate(-50%, -50%) scale(1.05); }
  }
  .level-announce .la-label {
    font-size: 10px;
    letter-spacing: 0.5em;
    color: var(--ink-dim);
    margin-bottom: 6px;
  }
  .level-announce .la-num {
    font-family: 'Major Mono Display', monospace;
    font-size: 64px;
    color: var(--accent-2);
    letter-spacing: 0.05em;
    text-shadow: 0 0 30px rgba(45, 226, 230, 0.5);
  }

  /* mix legend */
  .legend {
    display: grid;
    grid-template-columns: auto auto auto;
    gap: 10px 16px;
    font-size: 10px;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--ink-dim);
    margin-top: 4px;
  }
  .legend .row { display: contents; }
  .legend .sw {
    display: inline-block;
    width: 16px; height: 16px;
    border: 1px solid rgba(232,236,242,0.15);
    vertical-align: middle;
  }
  .legend .op { text-align: center; color: var(--ink-dim); }

  .corner {
    position: fixed;
    bottom: 6px;
    right: 8px;
    font-size: 9px;
    letter-spacing: 0.3em;
    color: var(--ink-dim);
    opacity: 0.5;
    text-transform: uppercase;
    pointer-events: none;
  }

  @media (max-height: 640px) {
    .target-panel { top: calc(max(12px, env(safe-area-inset-top)) + 48px); }
    .mini-tube { height: 28px; width: 12px; }
    .board-wrap { padding: 140px 12px 100px; }
    .tube { height: 170px; }
  }