:root {
    --card-size: 80px;
    --gap: 10px;
    --bg-dark: #1a1a2e;
    --bg-darker: #16162a;
    --text-primary: #f0f0f0;
    --text-secondary: #a0a0a0;
    --accent-color: #e94560;
    --accent-hover: #ff6b6b;
    --accent-green: #00ff88;
    --accent-cyan: #00d4ff;
    --border-color: #2a2a4a;
}

* {
    box-sizing: border-box;
}

body {
    background: var(--bg-dark);
    min-height: 100vh;
}

.game-container {
    max-width: 900px;
    margin: 0 auto;
    padding: 1rem;
}

.game-header {
    text-align: center;
    padding: 1.5rem;
    background: var(--bg-darker);
    border-radius: 12px;
    margin-bottom: 1rem;
}

.game-header h1 {
    font-size: 2rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--accent-cyan) 0%, var(--accent-green) 50%, var(--accent-color) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: 3px;
    text-transform: uppercase;
}

.game-controls {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}

.difficulty-select {
    padding: 0.75rem 1.5rem;
    font-size: 0.9rem;
    font-weight: 600;
    border: 2px solid var(--border-color);
    background: var(--bg-darker);
    color: var(--text-primary);
    border-radius: 8px;
    cursor: pointer;
}

.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    text-decoration: none;
    transition: all 0.2s ease;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.btn-primary {
    background: var(--accent-color);
    color: #fff;
}

.btn-primary:hover {
    background: var(--accent-hover);
}

.btn-secondary {
    background: transparent;
    color: var(--text-primary);
    border: 2px solid var(--border-color);
}

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

.game-stats {
    display: flex;
    justify-content: center;
    gap: 2rem;
    padding: 1rem;
    background: var(--bg-darker);
    border-radius: 8px;
    margin-bottom: 1rem;
}

.stat {
    text-align: center;
}

.stat-label {
    display: block;
    font-size: 0.7rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.stat-value {
    display: block;
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--text-primary);
}

.stat-value.green {
    color: var(--accent-green);
}

.game-board {
    display: flex;
    justify-content: center;
    padding: 1rem;
    background: var(--bg-darker);
    border-radius: 12px;
    overflow-x: auto;
}

.memory-grid {
    display: grid;
    gap: var(--gap);
    justify-content: center;
}

.mem-card {
    width: var(--card-size);
    height: var(--card-size);
    border-radius: 8px;
    cursor: pointer;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.3s ease;
}

.mem-card--flipped {
    transform: rotateY(180deg);
}

.mem-card--matched {
    opacity: 0.5;
    cursor: default;
}

.mem-card--disabled {
    pointer-events: none;
}

.mem-card-front,
.mem-card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
}

.mem-card-front {
    background: linear-gradient(135deg, #1e3c72 0%, #2a5298 100%);
    border: 2px solid var(--border-color);
}

.mem-card-back {
    background: #fff;
    transform: rotateY(180deg);
    border: 2px solid var(--accent-cyan);
}

.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
}

.modal.active {
    opacity: 1;
    visibility: visible;
}

.modal-body {
    background: var(--bg-darker);
    border-radius: 12px;
    padding: 2rem;
    text-align: center;
    max-width: 400px;
    width: 90%;
}

.modal-body h3 {
    color: var(--text-primary);
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

.modal-body p {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.win-stats {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 1.5rem;
}

@media (max-width: 600px) {
    :root {
        --card-size: 60px;
        --gap: 8px;
    }

    .game-header h1 {
        font-size: 1.5rem;
    }

    .game-stats {
        gap: 1rem;
    }

    .stat-value {
        font-size: 1rem;
    }
}

@media (min-width: 601px) and (max-width: 1024px) {
    :root {
        --card-size: 70px;
        --gap: 9px;
    }

    .game-header {
        padding: 1.25rem;
    }

    .game-header h1 {
        font-size: 1.75rem;
    }

    .game-stats {
        gap: 1.5rem;
        padding: 0.75rem;
    }

    .stat-value {
        font-size: 1.1rem;
    }

    .game-controls {
        gap: 0.75rem;
    }

    .difficulty-select {
        padding: 0.6rem 1.2rem;
        font-size: 0.85rem;
    }

    .btn {
        padding: 0.6rem 1.25rem;
        font-size: 0.85rem;
    }
}

@media (max-width: 480px) {
    :root {
        --card-size: 50px;
        --gap: 6px;
    }

    .game-controls {
        flex-direction: column;
    }

    .difficulty-select,
    .btn {
        width: 100%;
        text-align: center;
    }
}