html {
  font-size: 1px;
}

:root {
  --bg: #14161c;
  --panel: #1d2129;
  --board: #1d222c;
  --floor-rgb: 0, 88, 143;
  --floor-alpha: 0.08;
  --piece-fill: 0.14; /* fill only; piece rim + glow stay opaque */
  --piece-glow: 0.22;
  --piece-radius: 0.34; /* corner radius as fraction of cell */
  --grid-line-rgb: 92, 92, 92;
  --grid-line-alpha: 0.35;
  --grid-glow-rgb: 255, 255, 255;
  --grid-glow: 0;
  --rim-glow-rgb: 0, 0, 0;
  --rim-glow: 0.30; /* shared intensity: border wash + door wash */
  /* Falloff layers from curve editor (distance px + gain 0..1) */
  --rim-d0: 30.34; --rim-a0: 0.458;
  --rim-d1: 35.33; --rim-a1: 0.885;
  --rim-d2: 41.66; --rim-a2: 0.885;
  --rim-d3: 61.15; --rim-a3: 0.698;
  --grid-d0: 0.50; --grid-a0: 1.000;
  --grid-d1: 1.44; --grid-a1: 0.990;
  --grid-d2: 3.41; --grid-a2: 0.990;
  --grid-d3: 5.36; --grid-a3: 0.958;
  --piece-d0: 1.65; --piece-a0: 0.760;
  --piece-d1: 3.86; --piece-a1: 0.844;
  --piece-d2: 7.95; --piece-a2: 0.333;
  --piece-d3: 14.65; --piece-a3: 0.094;
  /* Slate frame rim */
  --frame: #273444;
  --frame-edge: #1a2430;
  --text: #e8eaf0;
  --text-dim: #8a90a0;
  --accent: #3e8ef7;
  /* Board geometry in px — JS overrides --cell; keep seam/cell out of rem scale */
  --cell: 32px;
  --stage-margin: 50rem;
  --seam: 2px;
  /*
   * Frame sits outside the cells with the same gap pieces use between each
   * other (each side insets --seam, so gap = 2×seam). Centerline is
   * seam + half stroke past the board edge → no overhang onto pieces.
   */
  --frame-stroke: 0.18;
  --frame-thick: calc(var(--cell) * var(--frame-stroke));
  --frame-outset: calc(var(--seam) + var(--frame-thick) / 2);
  --door-scale: 1.2;
  --door-thick: calc(var(--frame-thick) * var(--door-scale));
  /* Outer face of a door centered on the rim centerline */
  --door-outer: calc(var(--frame-outset) + var(--door-thick) / 2);
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html, body {
  height: 100%;
  overflow: hidden;
  overscroll-behavior: none;
  background: var(--bg);
  color: var(--text);
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  -webkit-user-select: none;
  -moz-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
  touch-action: none;
}

body {
  display: flex;
  flex-direction: column;
}

/* ---------- HUD ---------- */

.hud {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10rem 16rem;
  background: var(--panel);
  box-shadow: 0 2rem 8rem rgba(0, 0, 0, 0.35);
  z-index: 5;
}

.hud-left, .hud-right {
  display: flex;
  align-items: center;
  gap: 8rem;
}

.level-box {
  display: flex;
  align-items: center;
  gap: 8rem;
  background: rgba(255, 255, 255, 0.06);
  border-radius: 8rem;
  padding: 4rem 10rem;
}

.level-label {
  font-size: 11rem;
  letter-spacing: 1.5rem;
  color: var(--text-dim);
}

#levelInput {
  width: 58rem;
  background: transparent;
  border: none;
  color: var(--text);
  font-size: 20rem;
  font-weight: 700;
  text-align: center;
  outline: none;
  -moz-appearance: textfield;
}
#levelInput::-webkit-outer-spin-button,
#levelInput::-webkit-inner-spin-button { -webkit-appearance: none; }

.btn {
  background: rgba(255, 255, 255, 0.08);
  border: none;
  color: var(--text);
  font-size: 18rem;
  border-radius: 8rem;
  min-width: 36rem;
  height: 36rem;
  cursor: pointer;
  transition: background 0.15s;
}
.btn:hover { background: rgba(255, 255, 255, 0.16); }
.btn-wide { padding: 0 16rem; font-size: 14rem; font-weight: 600; }
.btn-primary { background: var(--accent); }
.btn-primary:hover { background: #5ba0f9; }

.stat {
  font-size: 13rem;
  color: var(--text-dim);
  font-variant-numeric: tabular-nums;
}

.btn-icon {
  font-size: 18rem;
  line-height: 1;
  padding: 0 2rem;
}

.btn-depot {
  min-width: 0;
  height: auto;
  padding: 6rem 10rem;
  font-size: 11rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-decoration: none;
  color: var(--text-dim);
  white-space: nowrap;
}
.btn-depot:hover { color: var(--text); }

/* ---------- Settings PIN pad ---------- */

.pin-screen {
  position: fixed;
  inset: 0;
  z-index: 40;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 16rem;
  background: rgba(8, 10, 14, 0.88);
}
.pin-screen.hidden { display: none; }

.pin-panel {
  width: min(280rem, calc(100vw - 32rem));
  padding: 16rem;
  background: var(--panel);
  border: 1rem solid rgba(255, 255, 255, 0.12);
  border-radius: 10rem;
  box-shadow: 0 10rem 28rem rgba(0, 0, 0, 0.55);
}

.pin-panel h2 {
  margin: 0 0 10rem;
  text-align: center;
  font-size: 14rem;
  letter-spacing: 0.2em;
  color: var(--text);
}

.pin-display {
  font: bold 22rem monospace;
  letter-spacing: 0.35em;
  text-align: center;
  color: var(--text);
  margin: 8rem 0 14rem;
  padding: 10rem 8rem;
  background: rgba(0, 0, 0, 0.35);
  border: 1rem solid rgba(255, 255, 255, 0.12);
  border-radius: 6rem;
}

.pin-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 6rem;
  margin-bottom: 10rem;
}

.pin-grid button {
  font-size: 16rem;
  font-weight: 700;
  padding: 12rem 0;
  cursor: pointer;
  color: var(--text);
  background: rgba(255, 255, 255, 0.08);
  border: none;
  border-radius: 8rem;
}
.pin-grid button:hover { background: rgba(255, 255, 255, 0.16); }

.pin-msg {
  min-height: 14rem;
  margin: 0 0 8rem;
  font-size: 11rem;
  letter-spacing: 0.08em;
  text-align: center;
  color: #f87171;
}

/* ---------- Draggable look panel ---------- */

.settings-panel {
  position: fixed;
  top: 56rem;
  right: 12rem;
  z-index: 20;
  width: 256rem;
  background: var(--panel);
  border: 1rem solid rgba(255, 255, 255, 0.12);
  border-radius: 10rem;
  box-shadow: 0 10rem 28rem rgba(0, 0, 0, 0.55);
  color: var(--text);
  overflow: hidden;
}
.settings-panel.hidden { display: none; }

.settings-titlebar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8rem;
  padding: 6rem 8rem 6rem 10rem;
  background: rgba(255, 255, 255, 0.06);
  cursor: grab;
  touch-action: none;
}
.settings-titlebar:active { cursor: grabbing; }
.settings-title {
  font-size: 11rem;
  font-weight: 700;
  letter-spacing: 1rem;
  text-transform: uppercase;
  color: var(--text-dim);
}
.settings-title-actions {
  display: flex;
  align-items: center;
  gap: 4rem;
}
.settings-tool {
  border: none;
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-dim);
  font-size: 10rem;
  font-weight: 600;
  padding: 3rem 8rem;
  border-radius: 5rem;
  cursor: pointer;
}
.settings-tool:hover { background: rgba(255, 255, 255, 0.14); color: var(--text); }
.settings-close {
  width: 22rem;
  height: 22rem;
  border: none;
  border-radius: 6rem;
  background: transparent;
  color: var(--text);
  font-size: 16rem;
  line-height: 1;
  cursor: pointer;
}
.settings-close:hover { background: rgba(255, 255, 255, 0.12); }
.btn-curve {
  flex: 0 0 22rem;
  width: 22rem;
  height: 22rem;
  border: none;
  border-radius: 5rem;
  background: rgba(255, 255, 255, 0.08);
  color: #8eb8f0;
  font-size: 13rem;
  line-height: 1;
  cursor: pointer;
  padding: 0;
}
.btn-curve:hover,
.btn-curve.active {
  background: rgba(62, 142, 247, 0.28);
  color: #fff;
}

.settings-body {
  display: flex;
  flex-direction: column;
  gap: 5rem;
  padding: 8rem 10rem 10rem;
}
.set-row {
  display: flex;
  align-items: center;
  gap: 6rem;
  min-height: 24rem;
  cursor: pointer;
}
.set-row > span:first-child {
  flex: 0 0 58rem;
  font-size: 10rem;
  letter-spacing: 0.4rem;
  color: var(--text-dim);
  text-transform: uppercase;
  white-space: nowrap;
}
.set-row input[type="color"] {
  flex: 0 0 24rem;
  width: 24rem;
  height: 20rem;
  padding: 0;
  border: 1rem solid rgba(255, 255, 255, 0.2);
  border-radius: 4rem;
  background: transparent;
  cursor: pointer;
}
.set-row input[type="color"]::-webkit-color-swatch-wrapper { padding: 1rem; }
.set-row input[type="color"]::-webkit-color-swatch {
  border: none;
  border-radius: 2rem;
}
.set-row input[type="range"] {
  flex: 1 1 auto;
  min-width: 0;
  accent-color: #c8d0dc;
  cursor: pointer;
}
.set-row input[type="checkbox"] {
  flex: 0 0 auto;
  width: 16rem;
  height: 16rem;
  accent-color: #3e8ef7;
  cursor: pointer;
}
.set-row em {
  flex: 0 0 2.8em;
  font-style: normal;
  font-size: 10rem;
  color: var(--text-dim);
  text-align: right;
  font-variant-numeric: tabular-nums;
}
.set-row-tight { margin-top: 2rem; padding: 0 2rem; }
.set-row-tight em { flex-basis: 2.8em; }

/* Floating falloff curve popup (shared by rim / grid / piece) */
.falloff-popup {
  position: fixed;
  top: 120rem;
  right: 280rem;
  z-index: 30;
  width: 260rem;
  padding: 0 10rem 10rem;
  background: var(--panel);
  border: 1rem solid rgba(255, 255, 255, 0.14);
  border-radius: 10rem;
  box-shadow: 0 12rem 32rem rgba(0, 0, 0, 0.55);
}
.falloff-popup.hidden { display: none; }
.falloff-popup-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8rem;
  margin: 0 -10rem 6rem;
  padding: 6rem 8rem 6rem 10rem;
  background: rgba(255, 255, 255, 0.06);
  cursor: grab;
  touch-action: none;
  border-radius: 10rem 10rem 0 0;
}
.falloff-popup-bar:active { cursor: grabbing; }
.falloff-popup-bar > span {
  font-size: 11rem;
  font-weight: 700;
  letter-spacing: 0.6rem;
  text-transform: uppercase;
  color: var(--text-dim);
}
#falloffCurve {
  display: block;
  width: 100%;
  height: 120rem;
  border-radius: 6rem;
  background: #12151a;
  border: 1rem solid rgba(255, 255, 255, 0.1);
  cursor: crosshair;
  touch-action: none;
}
.set-curve-axis {
  display: flex;
  justify-content: space-between;
  margin: 2rem 0 4rem;
  font-size: 9rem;
  color: var(--text-dim);
  opacity: 0.85;
}

/* ---------- Stage / board ---------- */

#stage {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  /* Fixed screen margin — door overhang is reserved in fitBoard, not here */
  padding: var(--stage-margin, 30rem);
}

#boardWrap { position: relative; }

/* Tron de-rez particles — sits above pieces, ignores hits */
.derez-canvas {
  position: absolute;
  left: 0;
  top: 0;
  z-index: 6;
  pointer-events: none;
}

#board {
  position: relative;
  /* width/height set per level from game.js (= bbox); voids are transparent */
  box-sizing: content-box;
  background: transparent;
  border: none;
  border-radius: 0;
  box-shadow: none;
  overflow: visible;
}

/* Playable cells — floor fill + glowing grid lines */
.play-cell {
  position: absolute;
  width: var(--cell);
  height: var(--cell);
  background: rgba(var(--floor-rgb), var(--floor-alpha));
  z-index: 0;
  pointer-events: none;
  overflow: hidden;
}
.play-cell::after {
  content: "";
  position: absolute;
  inset: 0;
  background:
    linear-gradient(rgba(var(--grid-line-rgb), var(--grid-line-alpha)) 1rem, transparent 1rem)
      0 0 / var(--cell) var(--cell),
    linear-gradient(90deg, rgba(var(--grid-line-rgb), var(--grid-line-alpha)) 1rem, transparent 1rem)
      0 0 / var(--cell) var(--cell);
  filter:
    drop-shadow(0 0 calc(var(--grid-glow) * var(--grid-d0) * 1rem) rgba(var(--grid-glow-rgb), calc(var(--grid-glow) * var(--grid-a0))))
    drop-shadow(0 0 calc(var(--grid-glow) * var(--grid-d1) * 1rem) rgba(var(--grid-glow-rgb), calc(var(--grid-glow) * var(--grid-a1))))
    drop-shadow(0 0 calc(var(--grid-glow) * var(--grid-d2) * 1rem) rgba(var(--grid-glow-rgb), calc(var(--grid-glow) * var(--grid-a2))))
    drop-shadow(0 0 calc(var(--grid-glow) * var(--grid-d3) * 1rem) rgba(var(--grid-glow-rgb), calc(var(--grid-glow) * var(--grid-a3))));
  pointer-events: none;
}

/* SVG stroke outside the cells — seam gap matches unconnected piece padding */
.board-frame {
  position: absolute;
  z-index: 4;
  pointer-events: none;
  overflow: visible;
}
/* Indirect light wash — layer distances/gains from Rim falloff curve */
.board-frame .frame-shade {
  fill: none;
  stroke: rgb(var(--rim-glow-rgb));
  stroke-width: calc(0.15 + var(--rim-glow) * var(--rim-a0) * 0.4);
  stroke-linecap: round;
  stroke-linejoin: round;
  opacity: calc(0.15 + var(--rim-glow) * var(--rim-a0) * 0.7);
}
.board-frame .frame-path {
  fill: none;
  stroke: var(--frame);
  stroke-width: var(--frame-stroke);
  stroke-linecap: round;
  stroke-linejoin: round;
  filter:
    drop-shadow(0 0 calc(var(--rim-glow) * var(--rim-d0) * 1rem) rgba(var(--rim-glow-rgb), calc(var(--rim-glow) * var(--rim-a0))))
    drop-shadow(0 0 calc(var(--rim-glow) * var(--rim-d1) * 1rem) rgba(var(--rim-glow-rgb), calc(var(--rim-glow) * var(--rim-a1))))
    drop-shadow(0 0 calc(var(--rim-glow) * var(--rim-d2) * 1rem) rgba(var(--rim-glow-rgb), calc(var(--rim-glow) * var(--rim-a2))))
    drop-shadow(0 0 calc(var(--rim-glow) * var(--rim-d3) * 1rem) rgba(var(--rim-glow-rgb), calc(var(--rim-glow) * var(--rim-a3))));
}

/* Sealed gate wall — opens when its unlock section is cleared */
.gate-cell {
  position: absolute;
  width: var(--cell);
  height: var(--cell);
  z-index: 1;
  pointer-events: none;
  background: var(--frame);
  border-radius: 4rem;
  box-shadow:
    inset 0 1rem 0 rgba(255, 255, 255, 0.45),
    inset 0 -2rem 3rem rgba(0, 0, 0, 0.18),
    inset 0 0 0 1rem var(--frame-edge),
    0 1rem 3rem rgba(0, 0, 0, 0.35);
  transition: opacity 0.28s ease, transform 0.28s ease;
}
.gate-cell .gate-stripe {
  position: absolute;
  inset: 18%;
  border-radius: 3rem;
  background: repeating-linear-gradient(
    -45deg,
    rgba(60, 50, 40, 0.22) 0 3rem,
    transparent 3rem 7rem
  );
}
.gate-cell.gate-open {
  opacity: 0;
  transform: scale(0.85);
}

/* Static interior pillars — muted glass blockers */
.pillar {
  position: absolute;
  width: var(--cell);
  height: var(--cell);
  z-index: 1;
  pointer-events: none;
  --block-color: #6b7280;
  --block-rgb: 107, 114, 128;
}
.pillar-surface {
  position: absolute;
  inset: var(--seam);
  border-radius: calc(var(--cell) * var(--piece-radius));
  background:
    linear-gradient(160deg, rgba(255, 255, 255, 0.12), transparent 45%),
    rgba(107, 114, 128, 0.45);
  box-shadow:
    inset 0 0 0 1.5rem rgba(180, 190, 205, 0.35),
    inset 0 0 10rem rgba(107, 114, 128, 0.25),
    0 0 8rem rgba(107, 114, 128, 0.2);
  backdrop-filter: blur(1rem);
}

/* ---------- Doors (1.2× rim, centered on border) ---------- */

.door {
  --door-color: #fff;
  /* Layer gains/distances from Rim falloff curve */
  --door-g0: color-mix(in srgb, var(--door-color) calc(var(--rim-glow) * var(--rim-a0) * 100%), transparent);
  --door-g1: color-mix(in srgb, var(--door-color) calc(var(--rim-glow) * var(--rim-a1) * 100%), transparent);
  --door-g2: color-mix(in srgb, var(--door-color) calc(var(--rim-glow) * var(--rim-a2) * 100%), transparent);
  --door-g3: color-mix(in srgb, var(--door-color) calc(var(--rim-glow) * var(--rim-a3) * 100%), transparent);
  --door-r0: calc(var(--rim-glow) * var(--rim-d0) * 1rem);
  --door-r1: calc(var(--rim-glow) * var(--rim-d1) * 1rem);
  --door-r2: calc(var(--rim-glow) * var(--rim-d2) * 1rem);
  --door-r3: calc(var(--rim-glow) * var(--rim-d3) * 1rem);
  --door-ox: 0rem;
  --door-oy: 0rem;
  --door-wash-inset:
    inset 0 1rem 0 rgba(255, 255, 255, 0.35),
    inset 0 -2rem 3rem rgba(0, 0, 0, 0.28);
  position: absolute;
  border-radius: 3rem;
  box-shadow:
    var(--door-ox) var(--door-oy) var(--door-r0) calc(var(--rim-glow) * var(--rim-d0) * 0.12rem) var(--door-g0),
    var(--door-ox) var(--door-oy) var(--door-r1) calc(var(--rim-glow) * var(--rim-d1) * 0.12rem) var(--door-g1),
    var(--door-ox) var(--door-oy) var(--door-r2) calc(var(--rim-glow) * var(--rim-d2) * 0.12rem) var(--door-g2),
    var(--door-ox) var(--door-oy) var(--door-r3) calc(var(--rim-glow) * var(--rim-d3) * 0.12rem) var(--door-g3),
    var(--door-wash-inset);
  z-index: 6;
  pointer-events: none;
}
/* Bias wash toward the board (under the door) */
.door.side-0 { --door-oy: calc(var(--rim-glow) * var(--rim-d1) * 0.45rem); }
.door.side-2 { --door-oy: calc(var(--rim-glow) * var(--rim-d1) * -0.45rem); }
.door.side-3 { --door-ox: calc(var(--rim-glow) * var(--rim-d1) * 0.45rem); }
.door.side-1 { --door-ox: calc(var(--rim-glow) * var(--rim-d1) * -0.45rem); }
.door::after {
  content: "";
  position: absolute;
  inset: 2rem;
  border-radius: 2rem;
  background: repeating-linear-gradient(
    45deg,
    rgba(255, 255, 255, 0.22) 0 4rem,
    transparent 4rem 8rem
  );
}
.door.tone-light {
  --door-wash-inset:
    inset 0 1rem 0 rgba(255, 255, 255, 0.65),
    inset 0 -2rem 3rem rgba(0, 0, 0, 0.18),
    inset 0 0 0 1rem rgba(0, 0, 0, 0.12);
}
.door.tone-dark {
  --door-wash-inset:
    inset 0 1rem 0 rgba(255, 255, 255, 0.22),
    inset 0 -2rem 3rem rgba(0, 0, 0, 0.55);
}
/* Outward chevron */
.door .chevron {
  position: absolute;
  left: 50%;
  top: 50%;
  width: 0;
  height: 0;
  transform: translate(-50%, -50%);
  z-index: 1;
  border-style: solid;
  border-color: transparent;
  filter: drop-shadow(0 1rem 1rem rgba(0, 0, 0, 0.35));
}
.door.side-0 .chevron { /* up */
  border-width: 0 5rem 7rem 5rem;
  border-bottom-color: rgba(255, 255, 255, 0.92);
}
.door.side-1 .chevron { /* right */
  border-width: 5rem 0 5rem 7rem;
  border-left-color: rgba(255, 255, 255, 0.92);
}
.door.side-2 .chevron { /* down */
  border-width: 7rem 5rem 0 5rem;
  border-top-color: rgba(255, 255, 255, 0.92);
}
.door.side-3 .chevron { /* left */
  border-width: 5rem 7rem 5rem 0;
  border-right-color: rgba(255, 255, 255, 0.92);
}

/* ---------- Blocks (translucent edge-lit glass, no knobs) ---------- */

.block {
  position: absolute;
  left: 0;
  top: 0;
  z-index: 2;
  cursor: grab;
  transition: transform 0.09s ease-out;
  filter:
    drop-shadow(0 0 calc(var(--piece-glow) * var(--piece-d0) * 1rem) rgba(var(--block-rgb), calc(var(--piece-glow) * var(--piece-a0))))
    drop-shadow(0 0 calc(var(--piece-glow) * var(--piece-d1) * 1rem) rgba(var(--block-rgb), calc(var(--piece-glow) * var(--piece-a1))))
    drop-shadow(0 0 calc(var(--piece-glow) * var(--piece-d2) * 1rem) rgba(var(--block-rgb), calc(var(--piece-glow) * var(--piece-a2))))
    drop-shadow(0 0 calc(var(--piece-glow) * var(--piece-d3) * 1rem) rgba(var(--block-rgb), calc(var(--piece-glow) * var(--piece-a3))))
    drop-shadow(0 2rem 4rem rgba(0, 0, 0, 0.4));
  will-change: transform;
}
.block.dragging {
  cursor: grabbing;
  z-index: 3;
  /* 1:1 finger follow — no laggy transition while dragging */
  transition: none;
  filter:
    drop-shadow(0 0 calc(var(--piece-glow) * var(--piece-d0) * 1.3rem) rgba(var(--block-rgb), calc(var(--piece-glow) * var(--piece-a0))))
    drop-shadow(0 0 calc(var(--piece-glow) * var(--piece-d1) * 1.3rem) rgba(var(--block-rgb), calc(var(--piece-glow) * var(--piece-a1))))
    drop-shadow(0 0 calc(var(--piece-glow) * var(--piece-d2) * 1.3rem) rgba(var(--block-rgb), calc(var(--piece-glow) * var(--piece-a2))))
    drop-shadow(0 6rem 10rem rgba(0, 0, 0, 0.55))
    brightness(1.08);
}
.block.settling {
  transition: transform 0.12s ease-out;
}
.block.exiting {
  transition: none;
  pointer-events: none;
  z-index: 5;
}
.block.exiting .bcell.is-out {
  visibility: hidden;
}
.block.denied { animation: shake 0.22s; }

@keyframes shake {
  0%, 100% { margin-left: 0; }
  25% { margin-left: -3rem; }
  75% { margin-left: 3rem; }
}

/* One grid cell of a piece — fused neighbors share flush edges → one silhouette */
.bcell {
  position: absolute;
  width: var(--cell);
  height: var(--cell);
}

/*
 * Flat translucent fill; 1rem bright outline inset 3rem on silhouette edges.
 */
.surface {
  position: absolute;
  inset: 0;
  overflow: hidden;
  background: rgba(var(--block-rgb), var(--piece-fill));
}

.surface::after {
  content: "";
  position: absolute;
  inset: 5rem;
  border-radius: inherit;
  pointer-events: none;
  border-style: solid;
  border-color: rgb(var(--block-rgb));
  border-width: 0;
  filter:
    drop-shadow(0 0 3rem rgb(var(--block-rgb)))
    drop-shadow(0 0 7rem rgba(var(--block-rgb), 0.9))
    drop-shadow(0 0 14rem rgba(var(--block-rgb), 0.65));
}
.surface.edge-t::after { border-top-width: 2rem; }
.surface.edge-r::after { border-right-width: 2rem; }
.surface.edge-b::after { border-bottom-width: 2rem; }
.surface.edge-l::after { border-left-width: 2rem; }

.tone-light .surface {
  background: rgba(var(--block-rgb), calc(var(--piece-fill) * 1.2));
}

/* Black tiles: inverted glass — deep smoke fill + gunmetal rim */
.block.tone-dark {
  filter:
    drop-shadow(0 0 calc(var(--piece-glow) * var(--piece-d0) * 1rem) rgba(90, 100, 115, calc(var(--piece-glow) * var(--piece-a0))))
    drop-shadow(0 0 calc(var(--piece-glow) * var(--piece-d1) * 1rem) rgba(70, 80, 95, calc(var(--piece-glow) * var(--piece-a1))))
    drop-shadow(0 0 calc(var(--piece-glow) * var(--piece-d2) * 1rem) rgba(50, 58, 70, calc(var(--piece-glow) * var(--piece-a2))))
    drop-shadow(0 2rem 4rem rgba(0, 0, 0, 0.45));
}
.block.tone-dark.dragging {
  filter:
    drop-shadow(0 0 calc(var(--piece-glow) * var(--piece-d0) * 1.3rem) rgba(110, 120, 140, calc(var(--piece-glow) * var(--piece-a0))))
    drop-shadow(0 0 calc(var(--piece-glow) * var(--piece-d1) * 1.3rem) rgba(80, 90, 110, calc(var(--piece-glow) * var(--piece-a1))))
    drop-shadow(0 6rem 10rem rgba(0, 0, 0, 0.55))
    brightness(1.06);
}
.tone-dark .surface {
  background: rgba(55, 62, 74, calc(var(--piece-fill) * 2.3));
}
.tone-dark .surface::after {
  border-color: rgb(120, 130, 148);
  filter:
    drop-shadow(0 0 3rem rgba(130, 140, 160, 0.9))
    drop-shadow(0 0 7rem rgba(95, 105, 125, 0.75))
    drop-shadow(0 0 14rem rgba(70, 80, 100, 0.5));
}

/* One-way arrows baked into each tile cell */
.axis-arrow {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  z-index: 4;
  pointer-events: none;
  filter: drop-shadow(0 0 3rem rgba(255, 255, 255, 0.65));
  opacity: 0.88;
}
.axis-arrow.axis-h {
  width: 58%;
  height: 22%;
  min-width: 14rem;
  min-height: 7rem;
  background: rgba(255, 255, 255, 0.92);
  clip-path: polygon(
    0% 50%, 20% 0%, 20% 32%, 80% 32%, 80% 0%,
    100% 50%, 80% 100%, 80% 68%, 20% 68%, 20% 100%
  );
}
.axis-arrow.axis-v {
  width: 22%;
  height: 58%;
  min-width: 7rem;
  min-height: 14rem;
  background: rgba(255, 255, 255, 0.92);
  clip-path: polygon(
    50% 0%, 100% 20%, 68% 20%, 68% 80%, 100% 80%,
    50% 100%, 0% 80%, 32% 80%, 32% 20%, 0% 20%
  );
}
.tone-light .axis-arrow.axis-h,
.tone-light .axis-arrow.axis-v {
  background: rgba(30, 36, 48, 0.7);
  filter: drop-shadow(0 0 2rem rgba(0, 0, 0, 0.35));
}

/* Glued dual-color pair marker */
.block.joined {
  filter:
    drop-shadow(0 0 calc(var(--piece-glow) * var(--piece-d0) * 1rem) rgba(var(--block-rgb), calc(var(--piece-glow) * var(--piece-a0))))
    drop-shadow(0 0 calc(var(--piece-glow) * var(--piece-d1) * 1rem) rgba(var(--block-rgb), calc(var(--piece-glow) * var(--piece-a1))))
    drop-shadow(0 0 calc(var(--piece-glow) * var(--piece-d2) * 1rem) rgba(255, 255, 255, calc(var(--piece-glow) * var(--piece-a2) * 0.4)))
    drop-shadow(0 2rem 4rem rgba(0, 0, 0, 0.45));
}
.join-badge {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  z-index: 5;
  width: 18rem;
  height: 18rem;
  margin-top: -1rem;
  border-radius: 50%;
  background: rgba(12, 14, 18, 0.55);
  color: #fff;
  font-size: 11rem;
  line-height: 18rem;
  text-align: center;
  pointer-events: none;
  box-shadow: 0 1rem 3rem rgba(0, 0, 0, 0.45);
}

/* ---------- Win overlay ---------- */

.overlay {
  position: fixed;
  inset: 0;
  background: rgba(10, 12, 16, 0.72);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 10;
  backdrop-filter: blur(3rem);
}
.overlay.hidden { display: none; }

.overlay-card {
  background: var(--panel);
  border-radius: 16rem;
  padding: 32rem 44rem;
  text-align: center;
  box-shadow: 0 16rem 60rem rgba(0, 0, 0, 0.6);
}
.overlay-card h1 { font-size: 30rem; margin-bottom: 8rem; }
.overlay-card p { color: var(--text-dim); margin-bottom: 22rem; }
.overlay-actions { display: flex; gap: 12rem; justify-content: center; }

/* ---------- Footer ---------- */

.foot {
  text-align: center;
  padding: 6rem;
  font-size: 11rem;
  color: var(--text-dim);
  font-variant-numeric: tabular-nums;
}