:root {
  --ink: #20252a;
  --paper: #f1efe6;
  --mist: #d9e4df;
  --line: rgba(32, 37, 42, 0.18);
  --accent: #b65d49;
  --accent-dark: #733b36;
  --board-size: min(58vw, 62vh, 640px);
  --puzzle-image: linear-gradient(145deg, #31525f 0 22%, #7d9b76 22% 43%, #ded88c 43% 57%, #b96451 57% 75%, #243f35 75% 100%);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  font-family: Athelas, Georgia, "Times New Roman", serif;
  background:
    linear-gradient(90deg, rgba(32, 37, 42, 0.055) 1px, transparent 1px),
    linear-gradient(rgba(32, 37, 42, 0.04) 1px, transparent 1px),
    var(--paper);
  background-size: 42px 42px;
  overflow: hidden;
}

button {
  border: 0;
  font: inherit;
}

.app {
  min-height: 100vh;
  display: grid;
  grid-template-rows: auto 1fr;
}

.panel {
  display: grid;
  grid-template-columns: minmax(170px, 1fr) auto auto;
  gap: 18px;
  align-items: center;
  padding: 18px clamp(16px, 3vw, 38px);
  border-bottom: 1px solid var(--line);
  background: rgba(241, 239, 230, 0.88);
  backdrop-filter: blur(14px);
  position: relative;
  z-index: 20;
}

.eyebrow {
  margin: 0 0 4px;
  color: var(--accent-dark);
  font-family: "Gill Sans", "Trebuchet MS", sans-serif;
  font-size: 0.76rem;
  font-weight: 700;
  letter-spacing: 0;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 4rem);
  line-height: 0.86;
  font-weight: 800;
}

.stats,
.controls {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: "Gill Sans", "Trebuchet MS", sans-serif;
}

.stats span {
  min-width: 104px;
  padding: 10px 12px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.43);
}

.stats strong {
  display: block;
  font-size: 1.35rem;
  line-height: 1;
}

.controls button {
  min-height: 44px;
  padding: 0 17px;
  color: #fff9ed;
  background: var(--ink);
  border: 1px solid rgba(32, 37, 42, 0.8);
  box-shadow: 0 6px 0 rgba(32, 37, 42, 0.24);
  cursor: pointer;
  transition: transform 160ms ease, box-shadow 160ms ease, background 160ms ease;
}

.controls button:hover,
.controls button:focus-visible {
  transform: translateY(-2px);
  box-shadow: 0 8px 0 rgba(32, 37, 42, 0.22);
}

.controls button:active {
  transform: translateY(3px);
  box-shadow: 0 3px 0 rgba(32, 37, 42, 0.2);
}

.controls .secondary {
  color: var(--ink);
  background: var(--mist);
}

.workspace {
  position: relative;
  min-height: 0;
  overflow: hidden;
}

.workspace::before {
  content: "";
  position: absolute;
  inset: 8%;
  border: 1px dashed rgba(32, 37, 42, 0.16);
  pointer-events: none;
}

.board-wrap {
  position: absolute;
  left: 50%;
  top: 52%;
  width: var(--board-size);
  transform: translate(-50%, -50%);
  text-align: center;
  z-index: 3;
}

.board {
  width: var(--board-size);
  aspect-ratio: 1 / 1;
  display: grid;
  grid-template: repeat(var(--rows, 5), 1fr) / repeat(var(--cols, 6), 1fr);
  border: 10px solid #fcfbf5;
  outline: 2px solid rgba(32, 37, 42, 0.26);
  background:
    linear-gradient(45deg, rgba(32, 37, 42, 0.08) 25%, transparent 25% 75%, rgba(32, 37, 42, 0.08) 75%),
    linear-gradient(45deg, rgba(32, 37, 42, 0.08) 25%, transparent 25% 75%, rgba(32, 37, 42, 0.08) 75%);
  background-color: rgba(255, 255, 255, 0.45);
  background-position: 0 0, 14px 14px;
  background-size: 28px 28px;
  box-shadow: 0 28px 70px rgba(32, 37, 42, 0.16);
}

.slot {
  border: 1px solid rgba(32, 37, 42, 0.14);
}

.hint {
  max-width: 520px;
  margin: 16px auto 0;
  color: rgba(32, 37, 42, 0.72);
  font-family: "Gill Sans", "Trebuchet MS", sans-serif;
  font-size: 0.96rem;
}

.piece {
  --x: 0px;
  --y: 0px;
  position: absolute;
  left: 0;
  top: 0;
  z-index: 5;
  padding: 0;
  border: 1px solid rgba(32, 37, 42, 0.38);
  border-radius: 5px;
  background-image: var(--puzzle-image);
  background-size: calc(var(--cols) * 100%) calc(var(--rows) * 100%);
  background-position: calc(var(--col) / (var(--cols) - 1) * 100%) calc(var(--row) / (var(--rows) - 1) * 100%);
  box-shadow: 0 9px 18px rgba(32, 37, 42, 0.22);
  touch-action: none;
  cursor: grab;
  transition: box-shadow 160ms ease, filter 160ms ease, scale 160ms ease;
}

.piece::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: linear-gradient(135deg, rgba(255, 255, 255, 0.24), transparent 44%, rgba(32, 37, 42, 0.12));
  pointer-events: none;
}

.piece.dragging {
  z-index: 30;
  cursor: grabbing;
  scale: 1.04;
  box-shadow: 0 20px 34px rgba(32, 37, 42, 0.34);
}

.piece.placed {
  z-index: 8;
  border-radius: 0;
  border-color: rgba(32, 37, 42, 0.08);
  box-shadow: none;
  cursor: default;
}

.reference {
  position: absolute;
  right: clamp(16px, 3vw, 38px);
  top: 24px;
  z-index: 16;
  width: min(27vw, 250px);
  padding: 10px;
  background: #fcfbf5;
  border: 1px solid var(--line);
  box-shadow: 0 18px 42px rgba(32, 37, 42, 0.18);
  transform: translateY(-12px);
  opacity: 0;
  pointer-events: none;
  transition: opacity 180ms ease, transform 180ms ease;
}

.reference.open {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.reference-image {
  aspect-ratio: 1 / 1;
  background-image: var(--puzzle-image);
  background-size: cover;
  border: 1px solid rgba(32, 37, 42, 0.18);
}

@media (max-width: 920px) {
  :root {
    --board-size: min(74vw, 54vh, 520px);
  }

  body {
    overflow: auto;
  }

  .app {
    min-height: 980px;
  }

  .panel {
    grid-template-columns: 1fr;
    align-items: start;
  }

  .stats,
  .controls {
    flex-wrap: wrap;
  }

  .workspace {
    min-height: 820px;
  }

  .board-wrap {
    top: 49%;
  }

  .reference {
    left: 16px;
    right: auto;
    width: 132px;
  }
}

@media (max-width: 560px) {
  :root {
    --board-size: min(88vw, 390px);
  }

  .app {
    min-height: 900px;
  }

  .workspace {
    min-height: 680px;
  }

  .stats span {
    min-width: 92px;
  }
}