:root {
  --bg: #f2ede1;
  --ink: #2c2620;
  --ink-soft: #8a7f68;
  --line: #d9cfb8;

  --wood-hi: #f0dcae;
  --wood-mid: #c99f5e;
  --wood-lo: #97702f;
  --wood-edge-lit: #f6e6bd;
  --wood-edge-dark: #5c3f1f;

  --slot-lo: #38270f;
  --slot-mid: #543c1a;
  --slot-rim: #6c4f24;

  --tile-hi: #ffffff;
  --tile-mid: #f7f2e7;
  --tile-lo: #e8e0cc;
  --tile-ink: #2a2419;
  --tile-rim: rgba(60, 40, 10, 0.28);
  --tile-shadow: rgba(50, 32, 8, 0.32);

  --correct-hi: #f8e9bb;
  --correct-mid: #d9ad4e;
  --correct-lo: #a8781f;
  --correct-ink: #3a2408;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  height: 100%;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
  overflow: hidden;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
}

.stage {
  height: 100%;
  display: flex;
  flex-direction: column;
  padding: 2.4vh 4vw 3vh;
}

/* ---- top bar ---- */

.topbar {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  flex-shrink: 0;
}

.brand {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
}

.back-link {
  display: flex;
  align-items: center;
  gap: 4px;
  margin-bottom: 0.8vh;
  color: var(--ink-soft);
  font-size: clamp(10px, 1.4vh, 12px);
  font-weight: 600;
  letter-spacing: 0.08em;
  text-decoration: none;
}
.back-link:hover { color: var(--ink); }
.back-link svg { width: 13px; height: 13px; }

.title {
  margin: 0;
  font-size: clamp(15px, 2.4vh, 20px);
  font-weight: 600;
  letter-spacing: 0.1em;
  color: var(--ink);
}

.brand-divider {
  display: flex;
  align-items: center;
  gap: 0.4em;
  margin: 0.5em 0 0.35em;
}

.brand-divider span {
  display: block;
  height: 1px;
  width: 1.2em;
  background: var(--line);
}

.brand-divider span.dot {
  width: 3px;
  height: 3px;
  border-radius: 50%;
  background: var(--line);
}

.subtitle {
  margin: 0;
  font-size: clamp(10px, 1.4vh, 12px);
  letter-spacing: 0.3em;
  color: var(--ink-soft);
}

.top-actions {
  display: flex;
  gap: 2vw;
}

.icon-btn {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1.5px solid var(--line);
  background: transparent;
  color: var(--ink);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: background 0.15s ease, transform 0.1s ease;
}

.icon-btn:active {
  background: rgba(38, 43, 40, 0.08);
  transform: scale(0.94);
}

.tagline {
  margin: 1.6vh 0 0;
  text-align: center;
  font-size: clamp(12px, 1.7vh, 14px);
  color: var(--ink-soft);
  letter-spacing: 0.03em;
  flex-shrink: 0;
}

/* ---- challenge banner ---- */

.challenge-banner {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 2vw;
  max-height: 0;
  opacity: 0;
  overflow: hidden;
  margin: 0 auto;
  padding: 0 4vw;
  border-radius: 999px;
  background: rgba(151, 112, 47, 0.14);
  border: 1.5px solid rgba(151, 112, 47, 0.35);
  color: var(--ink);
  font-size: clamp(11px, 1.6vh, 13px);
  letter-spacing: 0.02em;
  text-align: center;
  transition: max-height 0.35s ease, opacity 0.3s ease, margin 0.35s ease, padding 0.35s ease;
  flex-shrink: 0;
  cursor: pointer;
  border-color: rgba(151, 112, 47, 0.35);
}

.challenge-banner.show {
  max-height: 8vh;
  opacity: 1;
  margin: 1.4vh auto 0;
  padding: 1vh 4vw;
}

/* ---- board area ---- */

.board-area {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2.2vh;
  min-height: 0;
}

.board-wrap {
  position: relative;
  width: min(88vw, 66vh, 560px);
  aspect-ratio: 1 / 1;
}

.tray {
  position: absolute;
  inset: 0;
  border-radius: 8%;
  background:
    repeating-linear-gradient(94deg, rgba(255, 244, 220, 0.1) 0px, rgba(255, 244, 220, 0.1) 1px, transparent 1.5px, transparent 5px),
    linear-gradient(155deg, var(--wood-edge-lit) 0%, var(--wood-hi) 18%, var(--wood-mid) 55%, var(--wood-lo) 82%, var(--wood-edge-dark) 100%);
  box-shadow:
    inset 0 0 0 1px rgba(255, 255, 255, 0.25),
    inset 0 0.6vh 1.4vh rgba(255, 255, 255, 0.25),
    0 2vh 3.5vh rgba(60, 40, 15, 0.3);
}

.slots-grid,
.tiles-grid {
  position: absolute;
  left: 50%;
  top: 50%;
  width: 91%;
  height: 91%;
  transform: translate(-50%, -50%);
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-template-rows: repeat(4, 1fr);
  gap: 2.4%;
}

.tiles-grid {
  pointer-events: none;
}

.slot {
  border-radius: 16%;
  background: radial-gradient(circle at 38% 32%, var(--slot-mid) 0%, var(--slot-lo) 70%);
  box-shadow: inset 0 0.3vh 0.7vh rgba(0, 0, 0, 0.7), inset 0 0 0 1px var(--slot-rim);
}

.cell {
  position: relative;
}

/* ---- tiles ---- */

.tile {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: none;
  border-radius: 16%;
  pointer-events: auto;
  cursor: pointer;
  background: linear-gradient(155deg, var(--tile-hi) 0%, var(--tile-mid) 55%, var(--tile-lo) 100%);
  box-shadow:
    inset 0 0 0 1.5px var(--tile-rim),
    inset 0 0.4vh 0.5vh rgba(255, 255, 255, 0.5),
    inset 0 -0.5vh 0.6vh rgba(120, 70, 10, 0.35),
    0 0.4vh 0.6vh var(--tile-shadow);
  color: var(--tile-ink);
  font-size: clamp(18px, 4.6vh, 30px);
  font-weight: 700;
  font-family: inherit;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.25s cubic-bezier(.4,1.4,.6,1), box-shadow 0.2s ease;
  will-change: transform;
}

.tile.movable {
  box-shadow:
    inset 0 0 0 1.5px var(--tile-rim),
    inset 0 0.4vh 0.5vh rgba(255, 255, 255, 0.6),
    inset 0 -0.5vh 0.6vh rgba(120, 70, 10, 0.35),
    0 0.4vh 0.6vh var(--tile-shadow),
    0 0 0 1.5px rgba(151, 112, 47, 0.55),
    0 0 1.6vh rgba(151, 112, 47, 0.45);
}

.tile.movable.bounce {
  animation: tile-bounce 1.2s ease-in-out infinite;
}

@keyframes tile-bounce {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8%); }
}

.tile.correct {
  background: linear-gradient(155deg, var(--correct-hi) 0%, var(--correct-mid) 55%, var(--correct-lo) 100%);
  color: var(--correct-ink);
}

.tile.correct::after {
  content: "\2713";
  position: absolute;
  top: 7%;
  right: 11%;
  font-size: clamp(9px, 1.5vh, 12px);
  font-weight: 700;
  color: var(--correct-ink);
  opacity: 0.55;
}

.tile.shake {
  animation: shake 0.22s ease;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-6%); }
  75% { transform: translateX(6%); }
}

.tile:active {
  transform: scale(0.94);
}

/* ---- counter ---- */

.counter-box {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.3vh;
  padding: 1vh 3vh;
  border: 1.5px solid var(--line);
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.4);
}

.counter-label {
  font-size: clamp(9px, 1.3vh, 11px);
  letter-spacing: 0.18em;
  color: var(--ink-soft);
  text-transform: uppercase;
}

.counter-value {
  font-size: clamp(16px, 2.4vh, 20px);
  font-weight: 600;
  color: var(--ink);
  letter-spacing: 0.05em;
}

.counter-best {
  font-size: clamp(9px, 1.2vh, 11px);
  color: var(--ink-soft);
  letter-spacing: 0.06em;
  min-height: 1.4em;
}

/* ---- how to play ---- */

.howto-link {
  align-self: center;
  flex-shrink: 0;
  border: none;
  background: none;
  color: var(--ink-soft);
  font-size: clamp(12px, 1.8vh, 14px);
  letter-spacing: 0.05em;
  text-decoration: underline;
  text-underline-offset: 3px;
  cursor: pointer;
  padding: 1.2vh 4px 0;
}

.howto-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(20, 24, 22, 0.35);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
  z-index: 10;
}

.howto-backdrop.show {
  opacity: 1;
  pointer-events: auto;
}

.howto-sheet {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  background: var(--bg);
  border-radius: 20px 20px 0 0;
  box-shadow: 0 -1vh 3vh rgba(0, 0, 0, 0.25);
  padding: 1.6vh 6vw calc(4vh + env(safe-area-inset-bottom, 0px));
  transform: translateY(100%);
  transition: transform 0.35s cubic-bezier(.4,0,.2,1);
  z-index: 11;
}

.howto-sheet.show {
  transform: translateY(0);
}

.howto-handle {
  width: 36px;
  height: 4px;
  border-radius: 2px;
  background: var(--ink-soft);
  opacity: 0.4;
  margin: 0 auto 2vh;
}

.howto-title {
  margin: 0 0 1.6vh;
  font-size: clamp(14px, 2vh, 16px);
  font-weight: 600;
  letter-spacing: 0.1em;
  color: var(--ink);
}

.howto-list {
  margin: 0;
  padding: 0 0 0 1.1em;
  display: flex;
  flex-direction: column;
  gap: 1.2vh;
  font-size: clamp(13px, 1.9vh, 15px);
  color: var(--ink);
  line-height: 1.4;
}

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

.overlay {
  position: fixed;
  inset: 0;
  background: rgba(238, 241, 238, 0.95);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.5s ease;
}

.overlay.show {
  opacity: 1;
  pointer-events: auto;
}

.overlay-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2.2vh;
}

.overlay-title {
  margin: 0;
  font-size: clamp(18px, 3.4vh, 26px);
  font-weight: 600;
  letter-spacing: 0.3em;
  color: var(--ink);
}

.overlay-tile {
  width: 56px;
  height: 56px;
  border-radius: 16%;
  background: linear-gradient(155deg, var(--correct-hi) 0%, var(--correct-mid) 55%, var(--correct-lo) 100%);
  box-shadow:
    inset 0 0 0 1.5px var(--tile-rim),
    inset 0 0.4vh 0.5vh rgba(255, 255, 255, 0.5),
    0 0 3vh rgba(47, 143, 99, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  font-weight: 700;
  color: var(--correct-ink);
  animation: glow 1.6s ease-in-out infinite;
}

@keyframes glow {
  0%, 100% { box-shadow: inset 0 0 0 1.5px var(--tile-rim), inset 0 0.4vh 0.5vh rgba(255, 255, 255, 0.5), 0 0 1.5vh rgba(47, 143, 99, 0.5); }
  50% { box-shadow: inset 0 0 0 1.5px var(--tile-rim), inset 0 0.4vh 0.5vh rgba(255, 255, 255, 0.5), 0 0 3.5vh rgba(47, 143, 99, 0.9); }
}

.overlay-sub {
  margin: 0;
  font-size: clamp(12px, 1.8vh, 14px);
  color: var(--ink-soft);
  letter-spacing: 0.08em;
}

.overlay-actions {
  display: flex;
  gap: 3vw;
  margin-top: 1vh;
}

.again-btn,
.share-btn {
  padding: 1.2vh 4vw;
  border-radius: 999px;
  font-size: clamp(12px, 1.8vh, 14px);
  letter-spacing: 0.12em;
  cursor: pointer;
}

.again-btn {
  border: none;
  background: var(--ink);
  color: var(--bg);
}

.share-btn {
  border: 1.5px solid var(--ink);
  background: transparent;
  color: var(--ink);
}

.share-note {
  margin: 0;
  font-size: clamp(11px, 1.5vh, 13px);
  color: var(--ink-soft);
  letter-spacing: 0.06em;
  opacity: 0;
  transition: opacity 0.25s ease;
}

.share-note.show {
  opacity: 1;
}

@media (prefers-reduced-motion: reduce) {
  .tile { transition: none; }
  .tile.movable.bounce { animation: none; }
  .overlay-tile { animation: none; }
}