:root {
  --bg-color: #121212;
  --card-bg: #1e1e1e;
  --accent-color: #00ffcc;
  --accent-glow: rgba(0, 255, 204, 0.6);
  --text-color: #ffffff;
  --card-size: 100px;
  --gap: 15px;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  user-select: none;
}

body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  overflow: hidden;
}

/* HUD & Controls */
header {
  margin-bottom: 20px;
  text-align: center;
  z-index: 10;
}

h1 {
  font-size: 2.5rem;
  text-transform: uppercase;
  letter-spacing: 3px;
  text-shadow: 0 0 10px var(--accent-glow);
  margin-bottom: 10px;
}

.stats {
  display: flex;
  gap: 20px;
  font-size: 1.2rem;
  justify-content: center;
  margin-bottom: 15px;
}

.stat-box {
  background: rgba(255, 255, 255, 0.1);
  padding: 5px 15px;
  border-radius: 20px;
  border: 1px solid rgba(255, 255, 255, 0.1);
}

.controls {
  display: flex;
  gap: 15px;
  justify-content: center;
}

/* Game Grid */
.game-board {
  display: grid;
  grid-template-columns: repeat(4, var(--card-size));
  gap: var(--gap);
  perspective: 1000px;
  margin-bottom: 30px;
}

/* Card Styles */
.card {
  width: var(--card-size);
  height: var(--card-size);
  position: relative;
  transform-style: preserve-3d;
  transform: scale(1);
  transition: transform 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  cursor: pointer;
}

.card:active {
  transform: scale(0.95);
}

.card.flipped {
  transform: rotateY(180deg);
  cursor: default;
}

.card.matched {
  animation: pulse 1s infinite alternate;
  cursor: default;
}

.card-face {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.5);
}

/* Front Face (Hidden state) */
.card-front {
  background: linear-gradient(135deg, #2c3e50, #000000);
  border: 2px solid #333;
}

.card-front::after {
  content: "?";
  font-size: 2rem;
  color: rgba(255, 255, 255, 0.1);
}

/* Back Face (Revealed state) */
.card-back {
  background: var(--card-bg);
  border: 2px solid var(--accent-color);
  transform: rotateY(180deg);
  box-shadow: 0 0 15px var(--accent-glow) inset;
}

/* Buttons */
button {
  padding: 8px 20px;
  font-size: 0.9rem;
  background: transparent;
  color: var(--accent-color);
  border: 2px solid var(--accent-color);
  border-radius: 50px;
  cursor: pointer;
  transition: all 0.3s ease;
  text-transform: uppercase;
  letter-spacing: 2px;
  font-weight: bold;
}

button:hover {
  background: var(--accent-color);
  color: #000;
  box-shadow: 0 0 15px var(--accent-glow);
}

/* Modals */
.overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.85);
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  z-index: 100;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
  backdrop-filter: blur(5px);
}

.overlay.visible {
  opacity: 1;
  pointer-events: all;
}

.modal-content {
  background: #1a1a1a;
  padding: 30px;
  border-radius: 15px;
  border: 1px solid var(--accent-color);
  box-shadow: 0 0 30px var(--accent-glow);
  text-align: center;
  max-width: 90%;
  width: 400px;
}

.overlay h2 {
  font-size: 2.5rem;
  color: var(--accent-color);
  margin-bottom: 20px;
  text-shadow: 0 0 10px var(--accent-glow);
}

/* History Table */
.history-table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 20px;
  color: #ddd;
}

.history-table th,
.history-table td {
  padding: 10px;
  border-bottom: 1px solid #333;
}

.history-table th {
  color: var(--accent-color);
  text-transform: uppercase;
  font-size: 0.8rem;
  letter-spacing: 1px;
}

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

/* Particles for winning effect */
canvas {
  position: absolute;
  top: 0;
  left: 0;
  pointer-events: none;
  z-index: 50;
}

@keyframes pulse {
  0% {
    box-shadow: 0 0 10px var(--accent-glow);
  }
  100% {
    box-shadow:
      0 0 25px var(--accent-glow),
      0 0 5px white;
  }
}

/* Responsive */
@media (max-width: 500px) {
  :root {
    --card-size: 70px;
    --gap: 10px;
  }
  h1 {
    font-size: 1.8rem;
  }
  .game-board {
    grid-template-columns: repeat(4, var(--card-size));
  }
  .modal-content {
    padding: 20px;
  }
}