:root {
  --action-blue: #0066cc;
  --action-blue-focus: #0071e3;
  --canvas: #ffffff;
  --canvas-soft: #f5f5f7;
  --hairline: #d8d8df;
  --ink: #1d1d1f;
  --ink-muted: #6e6e73;
  --positive: #1d7f45;
  --surface-dark: #242426;
  --surface-mid: #e8eef8;

  color-scheme: light;
  font-family: "SF Pro Text", system-ui, -apple-system, BlinkMacSystemFont, "Inter", sans-serif;
  background: var(--canvas-soft);
  color: var(--ink);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at 82% 18%, rgba(0, 102, 204, 0.12), transparent 34%),
    linear-gradient(145deg, #ffffff 0%, #f5f5f7 46%, #eef3fb 100%);
}

button {
  font: inherit;
}

button:focus-visible {
  outline: 2px solid var(--action-blue-focus);
  outline-offset: 2px;
}

.shell {
  min-height: 100vh;
  display: grid;
  grid-template-rows: auto minmax(0, 1fr) auto auto;
  gap: 12px;
  padding: 24px 30px;
}

.hero {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 20px;
  border-bottom: 1px solid var(--hairline);
  padding-bottom: 16px;
}

.eyebrow {
  margin: 0 0 6px;
  color: var(--ink-muted);
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  font-size: 40px;
  line-height: 1;
  font-weight: 600;
}

.meta {
  display: flex;
  flex-wrap: wrap;
  justify-content: end;
  gap: 8px;
}

.meta span {
  border: 1px solid var(--hairline);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.84);
  padding: 8px 12px;
  font-size: 14px;
}

.play {
  align-self: center;
  display: grid;
  grid-template-columns: minmax(320px, 420px) minmax(210px, 260px);
  justify-content: center;
  align-items: stretch;
  gap: 16px;
}

.board {
  width: min(100%, 420px);
  aspect-ratio: 1;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  grid-template-rows: repeat(4, minmax(0, 1fr));
  gap: 10px;
  border: 1px solid var(--hairline);
  border-radius: 22px;
  background: var(--canvas);
  padding: 10px;
}

.card {
  min-width: 0;
  min-height: 0;
  border: 0;
  border-radius: 14px;
  background: var(--surface-dark);
  color: #ffffff;
  cursor: pointer;
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.08);
  transition:
    background-color 140ms cubic-bezier(0.16, 1, 0.3, 1),
    color 140ms cubic-bezier(0.16, 1, 0.3, 1),
    transform 140ms cubic-bezier(0.16, 1, 0.3, 1);
}

.card span {
  display: grid;
  place-items: center;
  min-height: 100%;
  font-size: clamp(17px, 4.8vw, 25px);
  font-weight: 700;
  letter-spacing: 0;
}

.card.visible {
  background: var(--action-blue);
}

.card.matched {
  background: #f1fbf5;
  color: var(--positive);
  box-shadow: inset 0 0 0 1px rgba(29, 127, 69, 0.24);
}

.card:hover:not(:disabled) {
  background: var(--action-blue-focus);
}

.card:active:not(:disabled) {
  transform: scale(0.96);
}

.card:disabled {
  cursor: default;
}

.panel {
  display: grid;
  gap: 10px;
}

.stat {
  display: grid;
  align-content: center;
  gap: 7px;
  border: 1px solid var(--hairline);
  border-radius: 18px;
  background: var(--canvas);
  padding: 16px;
}

.stat span {
  color: var(--ink-muted);
  font-size: 13px;
  font-weight: 600;
}

.stat strong {
  font-size: 24px;
  font-weight: 600;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
}

.actions button {
  min-width: 124px;
  border: 1px solid var(--action-blue);
  border-radius: 999px;
  background: var(--canvas);
  padding: 12px 20px;
  color: var(--action-blue);
  font-weight: 600;
  cursor: pointer;
  transition:
    background-color 140ms cubic-bezier(0.16, 1, 0.3, 1),
    transform 140ms cubic-bezier(0.16, 1, 0.3, 1);
}

.actions button:hover:not(:disabled) {
  background: #fafafc;
}

.actions button:active:not(:disabled) {
  transform: scale(0.96);
}

.actions button:disabled {
  cursor: default;
  opacity: 0.48;
}

.result,
.error {
  justify-self: stretch;
  margin: 0;
  border-radius: 18px;
  padding: 14px 16px;
  font-size: 14px;
}

.result {
  display: grid;
  gap: 6px;
  border: 1px solid var(--hairline);
  background: var(--canvas);
}

.result.solved {
  border-color: rgba(29, 127, 69, 0.28);
  background: #f1fbf5;
}

.result strong {
  font-size: 19px;
  font-weight: 600;
}

.result span {
  color: var(--ink-muted);
}

.error {
  background: #fff0f0;
  color: #d70015;
  font-weight: 600;
}

@media (max-width: 780px) {
  .shell {
    min-height: 100svh;
    grid-template-rows: auto auto auto auto;
    padding: 18px;
  }

  .hero {
    display: block;
  }

  .meta {
    justify-content: start;
    margin-top: 16px;
  }

  h1 {
    font-size: 34px;
  }

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

  .board {
    justify-self: center;
    gap: 7px;
    padding: 7px;
  }

  .card {
    border-radius: 10px;
  }

  .panel {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .stat {
    padding: 12px;
  }

  .stat strong {
    font-size: 18px;
  }
}

@media (max-width: 520px) {
  .panel {
    grid-template-columns: 1fr;
  }
}

@media (prefers-reduced-motion: reduce) {
  .card,
  .actions button {
    transition: none;
  }
}