:root {
  --bg0: #eff4ff;
  --bg1: #e0ecff;
  --panel: #ffffff;
  --line: #d1def0;
  --text: #10253f;
  --muted: #5c7390;
  --accent: #2d67df;
  --accent-strong: #1f53be;
  --light: #f2f7ff;
  --dark: #8fb2ea;
  --sel: #ffd66a;
  --hint: #7fe8ad;
}

* { box-sizing: border-box; }

.hidden { display: none !important; }

body {
  margin: 0;
  font-family: 'Space Grotesk', sans-serif;
  color: var(--text);
  background:
    radial-gradient(1000px 620px at 100% -20%, rgba(45, 103, 223, 0.12), transparent 62%),
    linear-gradient(180deg, var(--bg0), var(--bg1));
}

.app {
  max-width: 1200px;
  margin: 0 auto;
  padding: 22px 14px 26px;
}

.top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 12px;
  margin-bottom: 12px;
}

h1,
h2 {
  margin: 0;
  font-family: 'Sora', sans-serif;
}

h1 { font-size: clamp(1.8rem, 3vw, 2.45rem); }
h2 { font-size: 1.3rem; }

.sub {
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 0.93rem;
}

.back {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.9rem;
  padding-top: 6px;
}

.shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 360px;
  gap: 12px;
  align-items: start;
}

.panel {
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--panel);
  box-shadow: 0 12px 26px rgba(16, 36, 64, 0.08);
}

.board-panel {
  padding: 14px;
  transition: box-shadow 180ms ease, border-color 180ms ease;
}

.board-panel.shake {
  animation: shake 260ms ease;
}

.board-panel.flash-good {
  box-shadow: 0 0 0 2px rgba(127, 232, 173, 0.5), 0 12px 26px rgba(16, 36, 64, 0.08);
}

.board-panel.flash-bad {
  box-shadow: 0 0 0 2px rgba(255, 126, 126, 0.5), 0 12px 26px rgba(16, 36, 64, 0.08);
}

@keyframes shake {
  0% { transform: translateX(0); }
  20% { transform: translateX(-6px); }
  40% { transform: translateX(6px); }
  60% { transform: translateX(-5px); }
  80% { transform: translateX(5px); }
  100% { transform: translateX(0); }
}

.board {
  width: min(100%, 760px);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(8, minmax(0, 1fr));
  border: 1px solid #c7d7ea;
  border-radius: 12px;
  overflow: hidden;
  background: #d4e2f6;
}

.board-wrap {
  width: min(100%, 760px);
  margin: 0 auto;
  position: relative;
}

.move-fx-layer {
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: 3;
}

.square {
  aspect-ratio: 1;
  display: grid;
  place-items: center;
  border: 0;
  padding: 0;
  cursor: pointer;
  transition: filter 120ms ease;
}

.square.light { background: var(--light); }
.square.dark { background: var(--dark); }
.square.selectable {
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.42);
}
.square.selected {
  box-shadow: inset 0 0 0 4px var(--sel), inset 0 0 0 6px rgba(27, 45, 68, 0.2);
  filter: brightness(1.02);
}
.square.hint-from { box-shadow: inset 0 0 0 4px var(--sel); }
.square.hint-to { box-shadow: inset 0 0 0 4px var(--hint); }
.square.last-from {
  box-shadow: inset 0 0 0 3px rgba(173, 204, 255, 0.9);
}
.square.last-to {
  box-shadow: inset 0 0 0 3px rgba(120, 232, 173, 0.95);
}
.square:hover { filter: brightness(0.97); }

.piece-image {
  width: 86%;
  height: 86%;
  object-fit: contain;
  pointer-events: none;
  filter: drop-shadow(0 1px 1px rgba(12, 26, 45, 0.35));
}

.square.piece-fallback {
  font-size: clamp(1.26rem, 3.1vw, 2.25rem);
}

.info-panel {
  padding: 14px;
  display: grid;
  gap: 10px;
}

.chip-row {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.chip {
  border-radius: 999px;
  padding: 5px 10px;
  font-size: 0.76rem;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  font-weight: 700;
  background: #e8f1ff;
  color: #234d87;
  border: 1px solid #c6d8f1;
}

.chip.muted {
  background: #f6f9ff;
  color: var(--muted);
}

.prompt {
  margin: 0;
  color: #28496f;
  font-weight: 600;
}

.source {
  margin: 0;
  min-height: 1.1rem;
  color: var(--muted);
  font-size: 0.84rem;
}

.source a { color: #2e61a7; }

.stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 8px;
}

.stats article {
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #f8fbff;
  padding: 9px;
  text-align: center;
}

.stats span {
  color: var(--muted);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.stats strong {
  display: block;
  margin-top: 4px;
  font-size: 1.08rem;
}

.actions {
  display: grid;
  gap: 8px;
}

button {
  border: 1px solid var(--accent);
  border-radius: 10px;
  padding: 10px;
  background: linear-gradient(180deg, var(--accent), var(--accent-strong));
  color: #fff;
  font-weight: 700;
  cursor: pointer;
}

button:disabled {
  opacity: 0.72;
  cursor: not-allowed;
}

button.ghost {
  background: #f7fbff;
  border-color: #c4d6eb;
  color: #2f4f79;
}

.status {
  margin: 10px 0 0;
  min-height: 1.2rem;
  color: var(--muted);
  border-radius: 10px;
  border: 1px solid #d7e4f5;
  background: #f8fbff;
  padding: 8px 10px;
  font-size: 0.92rem;
}

.status.info {
  border-color: #d4e2f6;
  color: #37567f;
}

.status.good {
  border-color: rgba(127, 232, 173, 0.7);
  color: #1f7b4e;
  background: #f0fff6;
}

.status.bad {
  border-color: rgba(255, 126, 126, 0.64);
  color: #a83535;
  background: #fff4f4;
}

.solved-overlay {
  position: absolute;
  inset: 0;
  border-radius: 12px;
  background: linear-gradient(180deg, rgba(13, 33, 57, 0.2), rgba(13, 33, 57, 0.48));
  display: grid;
  place-items: center;
  pointer-events: none;
  animation: solvedFadeIn 220ms ease;
  z-index: 6;
}

.solved-card {
  min-width: min(82%, 320px);
  border-radius: 12px;
  border: 1px solid rgba(176, 233, 199, 0.88);
  background: linear-gradient(180deg, rgba(235, 255, 243, 0.97), rgba(222, 250, 235, 0.96));
  color: #1a5e3f;
  text-align: center;
  padding: 14px 16px 12px;
  box-shadow: 0 16px 30px rgba(11, 46, 32, 0.3);
  animation: solvedPop 280ms ease;
}

.solved-card h3 {
  margin: 0;
  font-family: 'Sora', sans-serif;
  font-size: 1.2rem;
}

.solved-card p {
  margin: 6px 0 0;
  font-size: 0.92rem;
}

.move-piece {
  position: absolute;
  left: 0;
  top: 0;
  width: var(--size, 56px);
  height: var(--size, 56px);
  transform: translate(calc(var(--sx) - 50%), calc(var(--sy) - 50%)) scale(1);
  transition: transform 220ms cubic-bezier(0.22, 0.64, 0.21, 1);
  filter: drop-shadow(0 4px 8px rgba(15, 36, 62, 0.45));
}

.move-piece.reply {
  transition-duration: 210ms;
  filter: drop-shadow(0 3px 6px rgba(15, 36, 62, 0.38));
}

.move-piece.go {
  transform: translate(calc(var(--tx) - 50%), calc(var(--ty) - 50%)) scale(1.02);
}

.move-piece-image {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.move-piece.piece-fallback {
  display: grid;
  place-items: center;
  font-size: clamp(1.2rem, 2.8vw, 2rem);
}

@keyframes solvedFadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes solvedPop {
  from { transform: translateY(10px) scale(0.95); opacity: 0; }
  to { transform: translateY(0) scale(1); opacity: 1; }
}

@media (max-width: 980px) {
  .shell {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 640px) {
  .app {
    padding: 16px 10px 20px;
  }

  .stats {
    grid-template-columns: 1fr;
  }
}