:root {
  --bg-primary: #0D1117;
  --bg-secondary: #161B22;
  --bg-tertiary: #21262D;
  --text-primary: #F0F6FC;
  --text-secondary: #8B949E;
  --text-muted: #484F58;
  --accent: #3B82F6;
  --border: #30363D;
  --btn-bg: #21262D;
  --btn-active: #30363D;
  --overlay-bg: rgba(0, 0, 0, 0.85);
  --board-bg: #0A0E14;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg-primary: #FFFFFF;
    --bg-secondary: #F6F8FA;
    --bg-tertiary: #E9ECF0;
    --text-primary: #1B1E28;
    --text-secondary: #57606A;
    --text-muted: #8C959F;
    --accent: #3182F6;
    --border: #D0D7DE;
    --btn-bg: #E9ECF0;
    --btn-active: #D0D7DE;
    --overlay-bg: rgba(255, 255, 255, 0.9);
    --board-bg: #F0F2F5;
  }
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  height: 100%;
  font-size: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Pretendard', 'Segoe UI', Roboto, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start;
  overflow-x: hidden;
}

/* ─── OVERLAY SCREENS ─── */
.overlay {
  position: fixed;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: var(--overlay-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  z-index: 100;
  padding: 24px;
  transition: opacity 0.3s ease;
}

.overlay.hidden {
  opacity: 0;
  pointer-events: none;
}

/* ─── START SCREEN ─── */
#start-screen {
  gap: 40px;
}

.title-wrap {
  text-align: center;
}

.title {
  font-size: clamp(3rem, 12vw, 5rem);
  font-weight: 800;
  letter-spacing: 0.08em;
  background: linear-gradient(135deg, var(--accent) 0%, #8B5CF6 50%, #EC4899 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
  margin-bottom: 8px;
}

.subtitle {
  font-size: 0.9rem;
  color: var(--text-muted);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.size-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  width: 100%;
  max-width: 340px;
}

.size-label {
  font-size: 0.8rem;
  color: var(--text-secondary);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.size-buttons {
  display: flex;
  gap: 10px;
  width: 100%;
}

.size-btn {
  flex: 1;
  padding: 12px 8px;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  background: var(--btn-bg);
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  text-align: center;
  line-height: 1.3;
}

.size-btn:hover {
  border-color: var(--accent);
  color: var(--text-primary);
  background: var(--btn-active);
}

.size-btn.active {
  border-color: var(--accent);
  background: var(--accent);
  color: #ffffff;
}

.size-btn .size-name {
  display: block;
  font-size: 0.95rem;
}

.size-btn .size-desc {
  display: block;
  font-size: 0.7rem;
  opacity: 0.75;
  margin-top: 2px;
}

.best-records {
  display: flex;
  flex-direction: column;
  gap: 6px;
  width: 100%;
  max-width: 340px;
}

.best-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 8px 14px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 8px;
}

.best-row-label {
  font-size: 0.78rem;
  color: var(--text-secondary);
}

.best-row-val {
  font-size: 0.78rem;
  color: var(--accent);
  font-weight: 700;
  letter-spacing: 0.02em;
}

.start-btn {
  width: 100%;
  max-width: 340px;
  padding: 16px;
  border: none;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--accent), #8B5CF6);
  color: #ffffff;
  font-family: inherit;
  font-size: 1.05rem;
  font-weight: 700;
  cursor: pointer;
  letter-spacing: 0.04em;
  transition: transform 0.15s ease, opacity 0.15s ease;
}

.start-btn:active {
  transform: scale(0.97);
  opacity: 0.9;
}

/* ─── VICTORY SCREEN ─── */
#victory-screen {
  gap: 32px;
}

.victory-emoji {
  font-size: 4rem;
  animation: bounce 0.6s ease infinite alternate;
}

@keyframes bounce {
  from { transform: translateY(0); }
  to   { transform: translateY(-12px); }
}

.victory-title {
  font-size: 2rem;
  font-weight: 800;
  background: linear-gradient(135deg, #FFD700, #FF8C00);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-align: center;
}

.victory-stats {
  display: flex;
  flex-direction: column;
  gap: 10px;
  width: 100%;
  max-width: 320px;
}

.stat-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 16px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 10px;
}

.stat-label {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.stat-value {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
}

.stat-value.new-best {
  color: #FFD700;
}

.new-best-badge {
  display: inline-block;
  font-size: 0.65rem;
  background: #FFD700;
  color: #1B1E28;
  padding: 2px 6px;
  border-radius: 4px;
  margin-left: 6px;
  font-weight: 800;
  vertical-align: middle;
  letter-spacing: 0.04em;
}

.victory-actions {
  display: flex;
  gap: 10px;
  width: 100%;
  max-width: 320px;
}

.btn-secondary {
  flex: 1;
  padding: 13px;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  background: var(--btn-bg);
  color: var(--text-primary);
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s ease;
}

.btn-secondary:hover {
  background: var(--btn-active);
}

.btn-primary {
  flex: 1;
  padding: 13px;
  border: none;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--accent), #8B5CF6);
  color: #ffffff;
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 700;
  cursor: pointer;
  transition: opacity 0.2s ease;
}

.btn-primary:active {
  opacity: 0.85;
}

/* ─── GAME LAYOUT ─── */
#game-screen {
  width: 100%;
  max-width: 480px;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  padding: 0 16px 24px;
}

/* ─── HEADER ─── */
.game-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 0 12px;
  gap: 8px;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 10px;
}

.header-title {
  font-size: 1.1rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--accent), #8B5CF6);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: 0.06em;
}

.icon-btn {
  width: 36px;
  height: 36px;
  border: 1.5px solid var(--border);
  border-radius: 8px;
  background: var(--btn-bg);
  color: var(--text-secondary);
  font-size: 1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s ease;
  flex-shrink: 0;
}

.icon-btn:hover {
  background: var(--btn-active);
  color: var(--text-primary);
}

/* ─── STATS BAR ─── */
.stats-bar {
  display: flex;
  gap: 10px;
  margin-bottom: 16px;
}

.stat-chip {
  flex: 1;
  padding: 10px 12px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 10px;
  text-align: center;
}

.stat-chip-label {
  font-size: 0.68rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 3px;
}

.stat-chip-value {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
}

/* ─── PROGRESS BAR ─── */
.progress-wrap {
  margin-bottom: 16px;
}

.progress-bar {
  width: 100%;
  height: 4px;
  background: var(--bg-tertiary);
  border-radius: 2px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), #8B5CF6);
  border-radius: 2px;
  transition: width 0.4s ease;
  width: 0%;
}

/* ─── BOARD ─── */
.board-wrap {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
}

.board {
  display: grid;
  gap: 8px;
  width: 100%;
  perspective: 1000px;
}

.board.grid-3x4 { grid-template-columns: repeat(3, 1fr); }
.board.grid-4x4 { grid-template-columns: repeat(4, 1fr); }
.board.grid-4x5 { grid-template-columns: repeat(4, 1fr); }

/* ─── CARD ─── */
.card {
  aspect-ratio: 1;
  position: relative;
  cursor: pointer;
  perspective: 600px;
  border-radius: 10px;
}

.card-inner {
  width: 100%;
  height: 100%;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.45s cubic-bezier(0.4, 0.2, 0.2, 1);
  border-radius: 10px;
}

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

.card-face {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 10px;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  border: 1.5px solid var(--border);
}

/* Back face */
.card-back {
  background: var(--bg-secondary);
  overflow: hidden;
}

.card-back::before {
  content: '';
  position: absolute;
  inset: 0;
  background:
    repeating-linear-gradient(
      45deg,
      transparent,
      transparent 6px,
      rgba(59, 130, 246, 0.06) 6px,
      rgba(59, 130, 246, 0.06) 12px
    ),
    repeating-linear-gradient(
      -45deg,
      transparent,
      transparent 6px,
      rgba(139, 92, 246, 0.06) 6px,
      rgba(139, 92, 246, 0.06) 12px
    );
}

.card-back-icon {
  font-size: 1.4rem;
  opacity: 0.25;
  position: relative;
  z-index: 1;
}

/* Front face */
.card-front {
  background: var(--bg-tertiary);
  transform: rotateY(180deg);
  font-size: clamp(1.2rem, 6vw, 2.2rem);
}

/* Matched state */
.card.matched .card-front {
  border-color: rgba(59, 130, 246, 0.6);
  background: var(--bg-secondary);
  box-shadow:
    0 0 0 1px rgba(59, 130, 246, 0.3),
    0 0 12px rgba(59, 130, 246, 0.2),
    0 0 24px rgba(59, 130, 246, 0.1);
}

.card.matched .card-inner {
  animation: matchPop 0.35s ease both;
}

@keyframes matchPop {
  0%   { transform: rotateY(180deg) scale(1); }
  50%  { transform: rotateY(180deg) scale(1.08); }
  100% { transform: rotateY(180deg) scale(1); }
}

/* Wrong shake */
.card.wrong .card-inner {
  animation: wrongShake 0.4s ease both;
}

@keyframes wrongShake {
  0%, 100% { transform: rotateY(180deg) translateX(0); }
  20%      { transform: rotateY(180deg) translateX(-5px); }
  40%      { transform: rotateY(180deg) translateX(5px); }
  60%      { transform: rotateY(180deg) translateX(-4px); }
  80%      { transform: rotateY(180deg) translateX(4px); }
}

/* ─── FOOTER ─── */
.game-footer {
  display: flex;
  justify-content: center;
  padding-top: 16px;
}

.restart-btn {
  padding: 10px 28px;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  background: var(--btn-bg);
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  letter-spacing: 0.03em;
  transition: all 0.2s ease;
}

.restart-btn:hover {
  background: var(--btn-active);
  color: var(--text-primary);
}

/* ─── RESPONSIVE TWEAKS ─── */
@media (max-width: 360px) {
  .board { gap: 6px; }
  .stats-bar { gap: 6px; }
}

@media (min-height: 700px) {
  .board { gap: 10px; }
}