:root {
  --bg: #0f1117;
  --bg-elev: #1a1d27;
  --bg-card-back: linear-gradient(135deg, #2a3450, #3b2a5c);
  --bg-card-front: #f5f3ef;
  --fg: #ecedf2;
  --fg-muted: #8a8fa3;
  --accent: #8b7dff;
  --accent-strong: #a497ff;
  --success: #5ad19a;
  --border: #262a38;
  --radius: 14px;
  --radius-sm: 10px;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial,
    "Apple Color Emoji", "Segoe UI Emoji", sans-serif;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  background: radial-gradient(
      1200px 800px at 20% -10%,
      rgba(139, 125, 255, 0.18),
      transparent 60%
    ),
    radial-gradient(
      900px 700px at 110% 10%,
      rgba(90, 209, 154, 0.10),
      transparent 60%
    ),
    var(--bg);
  color: var(--fg);
  font-family: var(--font);
  min-height: 100vh;
  min-height: 100dvh;
  -webkit-font-smoothing: antialiased;
}

#app {
  min-height: 100vh;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 24px 16px;
  gap: 24px;
}

h1 {
  font-size: clamp(28px, 5vw, 44px);
  margin: 0;
  letter-spacing: -0.02em;
  text-align: center;
}

h2 {
  font-size: 14px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--fg-muted);
  margin: 0 0 12px;
}

p {
  color: var(--fg-muted);
  line-height: 1.5;
  margin: 0;
}

button {
  font-family: inherit;
  font-size: 15px;
  font-weight: 600;
  color: var(--fg);
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px 16px;
  cursor: pointer;
  transition: transform 80ms ease, background 120ms ease, border-color 120ms ease;
}

button:hover {
  border-color: var(--accent);
}

button:active {
  transform: translateY(1px);
}

button.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #161325;
}

button.primary:hover {
  background: var(--accent-strong);
  border-color: var(--accent-strong);
}

button.ghost {
  background: transparent;
}

/* Start screen */

.start {
  width: 100%;
  max-width: 720px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 28px;
  margin-top: 4vh;
}

.subtitle {
  text-align: center;
  max-width: 520px;
}

.mode-tabs {
  display: flex;
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 4px;
  gap: 4px;
}

.mode-tabs button {
  background: transparent;
  border: none;
  border-radius: 999px;
  padding: 8px 18px;
  color: var(--fg-muted);
}

.mode-tabs button.active {
  background: var(--accent);
  color: #161325;
}

.options {
  width: 100%;
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
}

.option-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 10px;
  margin-bottom: 16px;
}

.option-card {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 4px;
  text-align: left;
  padding: 14px;
  border-radius: var(--radius-sm);
  background: #11141c;
  border: 1px solid var(--border);
  cursor: pointer;
}

.option-card:hover {
  border-color: var(--accent);
}

.option-card.selected {
  border-color: var(--accent);
  background: rgba(139, 125, 255, 0.12);
}

.option-name {
  font-weight: 600;
  font-size: 15px;
}

.option-meta {
  font-size: 12px;
  color: var(--fg-muted);
}

.option-best {
  font-size: 11px;
  color: var(--success);
  margin-top: 2px;
}

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

.start-actions > .ghost:first-child {
  margin-right: auto;
}

/* Game screen */

.game {
  width: 100%;
  max-width: 1100px;
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}

.hud {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.hud .spacer {
  flex: 1;
}

.stat {
  display: flex;
  flex-direction: column;
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 8px 14px;
  min-width: 88px;
}

.stat-label {
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--fg-muted);
}

.stat-value {
  font-size: 18px;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}

.board {
  --cols: 4;
  --rows: 3;
  --gap: 10px;
  display: grid;
  gap: var(--gap);
  grid-template-columns: repeat(var(--cols), minmax(0, 1fr));
  width: min(
    100%,
    calc(var(--cols) * 120px),
    calc((100dvh - 160px) * var(--cols) / var(--rows))
  );
  aspect-ratio: var(--cols) / var(--rows);
  margin: auto 0;
}

@media (max-width: 520px) {
  .board {
    --gap: 6px;
    width: min(
      100%,
      calc((100dvh - 120px) * var(--cols) / var(--rows))
    );
  }
}

.card {
  position: relative;
  aspect-ratio: 1 / 1;
  background: transparent;
  border: none;
  padding: 0;
  cursor: pointer;
  perspective: 800px;
  transition: opacity 200ms ease;
}

.card-inner {
  position: absolute;
  inset: 0;
  transform-style: preserve-3d;
  transition: transform 320ms cubic-bezier(0.2, 0.8, 0.2, 1);
  border-radius: var(--radius-sm);
}

.card.flipped .card-inner,
.card.matched .card-inner {
  transform: rotateY(180deg);
}

.card-face {
  position: absolute;
  inset: 0;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  user-select: none;
  box-shadow: inset 0 -3px 0 rgba(0, 0, 0, 0.18), var(--shadow);
}

.card-back {
  background: var(--bg-card-back);
  color: rgba(255, 255, 255, 0.35);
  font-size: clamp(18px, 3vw, 28px);
  font-weight: 700;
  letter-spacing: 0.1em;
}

.card-front {
  background: var(--bg-card-front);
  transform: rotateY(180deg);
  font-size: clamp(22px, 6vw, 52px);
}

.card.matched .card-inner {
  animation: matched 420ms ease;
}

.card.matched .card-front {
  background: #e8ffe8;
  box-shadow: inset 0 0 0 2px var(--success), var(--shadow);
}

@keyframes matched {
  0% {
    transform: rotateY(180deg) scale(1);
  }
  40% {
    transform: rotateY(180deg) scale(1.08);
  }
  100% {
    transform: rotateY(180deg) scale(1);
  }
}

.card:disabled {
  cursor: default;
}

/* Win screen */

.win {
  width: 100%;
  max-width: 520px;
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  box-shadow: var(--shadow);
  margin: auto 0;
}

.win-stats {
  display: flex;
  gap: 12px;
  width: 100%;
  justify-content: center;
}

.win-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(90, 209, 154, 0.15);
  color: var(--success);
  padding: 6px 12px;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 600;
}

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

/* Responsive tweaks */

@media (max-width: 520px) {
  #app {
    padding: 16px 10px;
  }

  .options {
    padding: 14px;
  }

}