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

:root {
  --bg: #0f0f0f;
  --surface: #1a1a1a;
  --border: #2a2a2a;
  --text: #f0ece0;
  --muted: #555;
  --yellow: #f5c842;
  --green: #4caf7d;
  --red: #e05c5c;
  --blue: #5c9fe0;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: "Syne Mono", monospace;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 2rem 1rem 3rem;
  position: relative;
  overflow-x: hidden;
}

/* subtle grid bg */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  background-image:
    linear-gradient(var(--border) 1px, transparent 1px),
    linear-gradient(90deg, var(--border) 1px, transparent 1px);
  background-size: 40px 40px;
  opacity: 0.3;
  pointer-events: none;
}

header {
  text-align: center;
  margin-bottom: 2rem;
  position: relative;
}

h1 {
  font-family: "Syne", sans-serif;
  font-weight: 800;
  font-size: clamp(2.5rem, 8vw, 4.5rem);
  letter-spacing: -0.03em;
  line-height: 1;
  color: var(--yellow);
  text-shadow: 4px 4px 0 #7a6010;
}

.tagline {
  font-size: 0.65rem;
  color: var(--muted);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  margin-top: 0.4rem;
}

/* Stats bar */
.stats {
  display: flex;
  gap: 2rem;
  margin-bottom: 1.5rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0.75rem 2rem;
}

.stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.2rem;
}

.stat-val {
  font-family: "Syne", sans-serif;
  font-weight: 700;
  font-size: 1.5rem;
  color: var(--yellow);
  line-height: 1;
}

.stat-label {
  font-size: 0.6rem;
  color: var(--muted);
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

.divider {
  width: 1px;
  background: var(--border);
  align-self: stretch;
}

/* Difficulty */
.difficulty {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}

.diff-btn {
  font-family: "Syne Mono", monospace;
  font-size: 0.65rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 0.4rem 1rem;
  border: 1px solid var(--border);
  border-radius: 2px;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  transition: all 0.15s;
}

.diff-btn:hover {
  border-color: var(--yellow);
  color: var(--yellow);
}
.diff-btn.active {
  background: var(--yellow);
  color: #0f0f0f;
  border-color: var(--yellow);
  font-weight: bold;
}

/* Grid */
.grid {
  display: grid;
  gap: 10px;
  margin-bottom: 1.5rem;
}

.grid.cols-4 {
  grid-template-columns: repeat(4, 1fr);
}
.grid.cols-5 {
  grid-template-columns: repeat(5, 1fr);
}
.grid.cols-6 {
  grid-template-columns: repeat(6, 1fr);
}

/* Card */
.card {
  aspect-ratio: 1;
  width: clamp(60px, 13vw, 90px);
  perspective: 600px;
  cursor: pointer;
}

.card-inner {
  width: 100%;
  height: 100%;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  border-radius: 6px;
}

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

.card-face {
  position: absolute;
  inset: 0;
  border-radius: 6px;
  backface-visibility: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
}

.card-back {
  background: var(--surface);
  border: 1px solid var(--border);
  font-size: 1.2rem;
  color: var(--border);
  transition: border-color 0.15s;
}

.card:hover:not(.flipped):not(.matched) .card-back {
  border-color: var(--yellow);
}

.card-front {
  background: var(--surface);
  border: 1px solid var(--border);
  transform: rotateY(180deg);
  font-size: clamp(1.4rem, 4vw, 2rem);
  border-radius: 6px;
}

.card.matched .card-front {
  border-color: var(--green);
  background: #0d2018;
  animation: matchPop 0.4s ease forwards;
}

@keyframes matchPop {
  0% {
    transform: rotateY(180deg) scale(1);
  }
  50% {
    transform: rotateY(180deg) scale(1.12);
  }
  100% {
    transform: rotateY(180deg) scale(1);
  }
}

.card.wrong .card-front {
  border-color: var(--red);
  background: #200d0d;
}

/* Controls */
.controls {
  display: flex;
  gap: 0.75rem;
}

.btn {
  font-family: "Syne Mono", monospace;
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 0.6rem 1.4rem;
  border: 1px solid var(--border);
  border-radius: 2px;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  transition: all 0.15s;
}

.btn:hover {
  border-color: var(--text);
  color: var(--text);
}

.btn-primary {
  background: var(--yellow);
  color: #0f0f0f;
  border-color: var(--yellow);
  font-weight: bold;
}

.btn-primary:hover {
  background: #ffd000;
  border-color: #ffd000;
  color: #0f0f0f;
}

/* Win overlay */
.overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.85);
  z-index: 100;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 1rem;
  text-align: center;
  padding: 2rem;
}

.overlay.show {
  display: flex;
  animation: fadeIn 0.3s ease;
}

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

.overlay h2 {
  font-family: "Syne", sans-serif;
  font-weight: 800;
  font-size: clamp(2rem, 8vw, 4rem);
  color: var(--yellow);
  text-shadow: 3px 3px 0 #7a6010;
  letter-spacing: -0.02em;
}

.overlay p {
  font-size: 0.75rem;
  color: var(--muted);
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

.overlay .final-stats {
  display: flex;
  gap: 2rem;
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 1rem 2rem;
  border-radius: 4px;
  margin: 0.5rem 0;
}

.overlay .final-stats .stat-val {
  font-size: 2rem;
}

/* Timer color feedback */
.timer-warn {
  color: var(--red) !important;
}