/* CSS Variables for theming */
:root {
    --bg-color: #f0f2f5;
    --card-bg: #ffffff;
    --card-shadow: rgba(0, 0, 0, 0.1);
    --text-color: #333333;
    --primary-color: #4a90e2;
    --success-color: #28a745;
    --danger-color: #dc3545;
    --border-color: #e1e5e9;
    --modal-bg: rgba(0, 0, 0, 0.5);
}

[data-theme="dark"] {
    --bg-color: #1a1a1a;
    --card-bg: #2d2d2d;
    --card-shadow: rgba(255, 255, 255, 0.1);
    --text-color: #ffffff;
    --primary-color: #5aa3f0;
    --success-color: #32d74b;
    --danger-color: #ff453a;
    --border-color: #404040;
    --modal-bg: rgba(0, 0, 0, 0.8);
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: var(--bg-color);
    color: var(--text-color);
    min-height: 100vh;
    transition: all 0.3s ease;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
}

h1 {
    font-size: 2.5rem;
    text-align: center;
    color: var(--primary-color);
    text-shadow: 2px 2px 4px var(--card-shadow);
}

.theme-toggle button {
    background: var(--card-bg);
    border: 2px solid var(--border-color);
    border-radius: 50%;
    width: 50px;
    height: 50px;
    font-size: 1.5rem;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 2px 10px var(--card-shadow);
}

.theme-toggle button:hover {
    transform: scale(1.1);
    box-shadow: 0 4px 15px var(--card-shadow);
}

.game-stats {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.stat {
    background: var(--card-bg);
    padding: 15px 25px;
    border-radius: 10px;
    box-shadow: 0 4px 15px var(--card-shadow);
    text-align: center;
    min-width: 120px;
}

.stat .label {
    display: block;
    font-size: 0.9rem;
    color: var(--text-color);
    opacity: 0.7;
    margin-bottom: 5px;
}

.stat span:last-child {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

.game-controls {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-bottom: 30px;
    flex-wrap: wrap;
}

.game-controls button,
.game-controls select {
    padding: 12px 20px;
    border: none;
    border-radius: 8px;
    background: var(--primary-color);
    color: white;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px var(--card-shadow);
}

.game-controls button:hover,
.game-controls select:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px var(--card-shadow);
}

.game-board {
    display: grid;
    gap: 15px;
    justify-content: center;
    margin-bottom: 40px;
    perspective: 1000px;
}

.game-board.grid-4 {
    grid-template-columns: repeat(4, 100px);
    grid-template-rows: repeat(4, 100px);
}

.game-board.grid-6 {
    grid-template-columns: repeat(6, 80px);
    grid-template-rows: repeat(6, 80px);
}

.card {
    background: var(--card-bg);
    border-radius: 12px;
    cursor: pointer;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.6s ease;
    box-shadow: 0 4px 15px var(--card-shadow);
    border: 2px solid var(--border-color);
}

.card:hover {
    transform: scale(1.05);
}

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

.card.matched {
    transform: rotateY(180deg) scale(1.1);
    border-color: var(--success-color);
    box-shadow: 0 0 20px rgba(40, 167, 69, 0.3);
}

.card.shake {
    animation: shake 0.5s ease-in-out;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-5px); }
    75% { transform: translateX(5px); }
}

.card-face {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    border-radius: 10px;
}

.card-back {
    background: linear-gradient(135deg, var(--primary-color), #357abd);
    color: white;
    font-size: 1.5rem;
}

.card-front {
    background: var(--card-bg);
    transform: rotateY(180deg);
    color: var(--text-color);
}

.leaderboard {
    background: var(--card-bg);
    border-radius: 15px;
    padding: 25px;
    box-shadow: 0 4px 20px var(--card-shadow);
    border: 2px solid var(--border-color);
}

.leaderboard h3 {
    text-align: center;
    margin-bottom: 20px;
    color: var(--primary-color);
    font-size: 1.5rem;
}

.leaderboard-entry {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 15px;
    margin-bottom: 10px;
    background: var(--bg-color);
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
}

.leaderboard-entry:nth-child(2) { border-left-color: #ffd700; }
.leaderboard-entry:nth-child(3) { border-left-color: #c0c0c0; }
.leaderboard-entry:nth-child(4) { border-left-color: #cd7f32; }

.leaderboard-entry .rank {
    font-weight: bold;
    font-size: 1.2rem;
    margin-right: 15px;
}

.leaderboard-entry .name {
    flex-grow: 1;
    font-weight: 600;
}

.leaderboard-entry .stats {
    display: flex;
    gap: 15px;
    font-size: 0.9rem;
    opacity: 0.8;
}

/* Modal Styles */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--modal-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    transition: opacity 0.3s ease;
}

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

.modal-content {
    background: var(--card-bg);
    padding: 40px;
    border-radius: 20px;
    text-align: center;
    max-width: 500px;
    width: 90%;
    box-shadow: 0 10px 40px var(--card-shadow);
    border: 2px solid var(--border-color);
    transform: scale(0.9);
    transition: transform 0.3s ease;
}

.modal:not(.hidden) .modal-content {
    transform: scale(1);
}

.modal-content h2 {
    color: var(--success-color);
    margin-bottom: 20px;
    font-size: 2rem;
}

.final-stats {
    margin: 20px 0;
    padding: 20px;
    background: var(--bg-color);
    border-radius: 10px;
    border: 2px solid var(--border-color);
}

.final-stats p {
    margin: 10px 0;
    font-size: 1.2rem;
    font-weight: 600;
}

.name-input {
    margin: 25px 0;
}

.name-input label {
    display: block;
    margin-bottom: 10px;
    font-weight: 600;
}

.name-input input {
    width: 100%;
    padding: 12px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    background: var(--bg-color);
    color: var(--text-color);
    transition: border-color 0.3s ease;
}

.name-input input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.modal-buttons {
    display: flex;
    gap: 15px;
    justify-content: center;
    flex-wrap: wrap;
}

.modal-buttons button {
    padding: 12px 25px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
    min-width: 120px;
}

#save-score-btn {
    background: var(--success-color);
    color: white;
}

#play-again-btn {
    background: var(--primary-color);
    color: white;
}

.modal-buttons button:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 15px var(--card-shadow);
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 15px;
    }
    
    h1 {
        font-size: 2rem;
    }
    
    .game-stats {
        gap: 15px;
    }
    
    .stat {
        padding: 10px 15px;
        min-width: 100px;
    }
    
    .game-board.grid-4 {
        grid-template-columns: repeat(4, 80px);
        grid-template-rows: repeat(4, 80px);
        gap: 10px;
    }
    
    .game-board.grid-6 {
        grid-template-columns: repeat(6, 60px);
        grid-template-rows: repeat(6, 60px);
        gap: 8px;
    }
    
    .card-face {
        font-size: 1.5rem;
    }
    
    .game-board.grid-6 .card-face {
        font-size: 1.2rem;
    }
    
    .modal-content {
        padding: 25px;
        margin: 20px;
    }
    
    .leaderboard-entry {
        flex-direction: column;
        text-align: center;
        gap: 10px;
    }
    
    .leaderboard-entry .stats {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .game-board.grid-4 {
        grid-template-columns: repeat(4, 70px);
        grid-template-rows: repeat(4, 70px);
    }
    
    .game-board.grid-6 {
        grid-template-columns: repeat(6, 50px);
        grid-template-rows: repeat(6, 50px);
    }
    
    .card-face {
        font-size: 1.2rem;
    }
    
    .game-board.grid-6 .card-face {
        font-size: 1rem;
    }
}