body {
    font-family: 'Segoe UI', Tahoma, sans-serif;
    text-align: center;
    background: linear-gradient(135deg, #89f7fe, #66a6ff);
    margin: 0;
    padding: 0;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    user-select: none;
}

h1 {
    margin-top: 30px;
    color: white;
    text-shadow: 2px 2px 8px rgba(0,0,0,0.3);
    user-select: none;
}

.grid {
    display: grid;
    grid-template-columns: repeat(6, 90px);
    gap: 12px;
    justify-content: center;
    margin-top: 40px;
    user-select: none;
}

.card {
    width: 90px;
    height: 90px;
    background: #ffffff;
    border-radius: 10px;
    box-shadow: 0 4px 10px rgba(0,0,0,0.2);
    cursor: pointer;
    font-size: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    transform: scale(1);
    transition: transform 0.2s ease, background 0.3s ease;
    user-select: none;
}

.card:hover {
    transform: scale(1.05);
    background: #f1f1f1;
    user-select: none;
}

  .flipped {
    background: white;
    animation: flip 0.3s ease;
    user-select: none;
  }

@keyframes flip {
    0% { transform: rotateY(0deg); }
    50% { transform: rotateY(90deg); }
    100% { transform: rotateY(0deg); }
  }

.matched {
    background: #32cd32;
    color: white;
    animation: match 0.5s ease;
    user-select: none;
}

@keyframes match {
    0% { transform: scale(1); }
    50% { transform: scale(1.2); }
    100% { transform: scale(1); }
}

.controls {
    width: 100%;
    display: flex;
    justify-content: center;
    margin: 30px 0 60px 0;
    user-select: none;
}

.back-btn {
    display: inline-block;
    text-decoration: none;
    padding: 12px 20px;
    border-radius: 12px;
    background: rgba(255,255,255,0.95);
    color: #3a3a3a;
    box-shadow: 0 6px 18px rgba(0,0,0,0.15);
    font-weight: 600;
    transition: transform 0.15s ease, box-shadow 0.15s ease;
    user-select: none;
}

.back-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 24px rgba(0,0,0,0.18);
    user-select: none;
}