body {
    --glass-bg: var(--cp-glass-bg);
    --glass-border: var(--cp-glass-border);
    --glass-highlight: var(--cp-glass-highlight);
    --glass-shadow: var(--cp-shadow);
    --text-primary: var(--cp-text);
    --text-muted: var(--cp-text-muted);
    --accent: var(--cp-accent);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Outfit', sans-serif;
}

body {
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    color: var(--text-primary);
    overflow: hidden;
    position: relative;
}

/* Back Button */
.back-btn {
    position: absolute;
    top: 2rem;
    left: 2rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 600;
    padding: 0.8rem 1.5rem;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 30px;
    backdrop-filter: blur(10px);
    transition: all 0.3s ease;
    z-index: 50;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.back-btn:hover {
    background: var(--glass-highlight);
    transform: translateX(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
}

/* Glassmorphism Container */
.game-container {
    background: var(--glass-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--glass-border);
    border-top: 1px solid var(--glass-highlight);
    border-left: 1px solid var(--glass-highlight);
    border-radius: 30px;
    padding: 2.5rem;
    box-shadow: var(--glass-shadow);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1.5rem;
    width: 90%;
    max-width: 480px;
    z-index: 10;
    position: relative;
    overflow: hidden;
}

.game-container::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 50%;
    height: 100%;
    background: linear-gradient(to right, transparent, rgba(255, 255, 255, 0.05), transparent);
    transform: skewX(-25deg);
    animation: glassShine 8s infinite;
}

@keyframes glassShine {
    0% { left: -100%; }
    20%, 100% { left: 200%; }
}

header {
    width: 100%;
    text-align: center;
}

.glow-text {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 1rem;
    color: transparent;
    -webkit-text-stroke: 1px rgba(255, 255, 255, 0.8);
    background: linear-gradient(to right, #fff, rgba(255, 255, 255, 0.5));
    -webkit-background-clip: text;
    background-clip: text;
    text-shadow: 0 4px 10px rgba(0, 0, 0, 0.3);
    letter-spacing: 2px;
    text-transform: uppercase;
}

.scores {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    width: 100%;
}

.score-card {
    background: rgba(255, 255, 255, 0.03);
    padding: 0.5rem 1.5rem;
    border-radius: 16px;
    border: 1px solid var(--glass-border);
    backdrop-filter: blur(5px);
    display: flex;
    flex-direction: column;
    align-items: center;
    min-width: 100px;
    transition: all 0.3s ease;
}

.personal-best {
    border-color: rgba(255, 204, 112, 0.4);
    box-shadow: 0 0 15px rgba(255, 204, 112, 0.1);
}

.player-label {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.score-value {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--accent);
    text-shadow: 0 0 10px var(--cp-accent-glow);
}

.personal-best .score-value {
    color: #ffcc70;
    text-shadow: 0 0 10px rgba(255, 204, 112, 0.5);
}

/* Board */
.board-wrapper {
    position: relative;
    padding: 10px;
    background: rgba(0, 0, 0, 0.2);
    border-radius: 16px;
    border: 1px solid var(--glass-border);
    box-shadow: inset 0 5px 15px rgba(0, 0, 0, 0.3);
}

.grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-template-rows: repeat(4, 1fr);
    gap: 8px;
    width: 340px;
    height: 340px;
    position: relative;
}

.cell {
    background: rgba(255, 255, 255, 0.05);
    border-radius: 12px;
    border: 1px solid rgba(255, 255, 255, 0.05);
}

/* Tiles are absolutely positioned and animated via transform */
.tile {
    position: absolute;
    top: 0;
    left: 0;
    border-radius: 12px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 2rem;
    font-weight: 800;
    user-select: none;
    z-index: 2;
    /* transform is set by JS for smooth sliding */
}

/* Tile Colors */
.tile[data-value="2"] {
    background: rgba(238, 228, 218, 0.9);
    color: #776e65;
}

.tile[data-value="4"] {
    background: rgba(237, 224, 200, 0.9);
    color: #776e65;
}

.tile[data-value="8"] {
    background: rgba(242, 177, 121, 0.95);
    color: #fff;
}

.tile[data-value="16"] {
    background: rgba(245, 149, 99, 0.95);
    color: #fff;
}

.tile[data-value="32"] {
    background: rgba(246, 124, 95, 0.95);
    color: #fff;
}

.tile[data-value="64"] {
    background: rgba(246, 94, 59, 0.95);
    color: #fff;
}

.tile[data-value="128"] {
    background: rgba(237, 207, 114, 0.95);
    color: #fff;
    font-size: 1.8rem;
    box-shadow: 0 0 20px rgba(237, 207, 114, 0.4);
}

.tile[data-value="256"] {
    background: rgba(237, 204, 97, 0.95);
    color: #fff;
    font-size: 1.8rem;
    box-shadow: 0 0 25px rgba(237, 204, 97, 0.5);
}

.tile[data-value="512"] {
    background: rgba(237, 200, 80, 0.95);
    color: #fff;
    font-size: 1.8rem;
    box-shadow: 0 0 30px rgba(237, 200, 80, 0.5);
}

.tile[data-value="1024"] {
    background: rgba(237, 197, 63, 0.95);
    color: #fff;
    font-size: 1.5rem;
    box-shadow: 0 0 35px rgba(237, 197, 63, 0.6);
}

.tile[data-value="2048"] {
    background: rgba(237, 194, 46, 0.95);
    color: #fff;
    font-size: 1.5rem;
    box-shadow: 0 0 40px rgba(237, 194, 46, 0.8);
}

/* For super tiles beyond 2048 */
.tile.super {
    background: linear-gradient(135deg, #3c3a32, #1a1a2e);
    color: #fff;
    font-size: 1.3rem;
    box-shadow: 0 0 40px rgba(0, 255, 204, 0.5);
}

.tile.pop {
    animation: tilePop 0.2s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

@keyframes tilePop {
    0%   { scale: 1; }
    40%  { scale: 1.2; }
    100% { scale: 1; }
}

/* Overlay */
.overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(8px);
    border-radius: 16px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 1rem;
    transition: opacity 0.3s ease;
    opacity: 1;
    z-index: 20;
}

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

.game-over-text {
    font-size: 2.2rem;
    color: #ff3366;
    text-shadow: 0 0 20px rgba(255, 51, 102, 0.6);
    margin: 0;
}

.final-score-text {
    font-size: 1.2rem;
    color: var(--text-muted);
}

.final-score-text span {
    color: var(--accent);
    font-weight: 800;
}

/* Game Controls */
.game-controls {
    display: flex;
    gap: 1rem;
}

/* Button */
.btn {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--glass-border);
    border-top: 1px solid var(--glass-highlight);
    border-left: 1px solid var(--glass-highlight);
    padding: 0.8rem 2rem;
    border-radius: 30px;
    color: var(--text-primary);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 1px;
    position: relative;
    overflow: hidden;
}

.btn:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
}

.btn:active {
    transform: translateY(1px);
}

/* Mobile Controls */
.mobile-controls {
    display: none;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    margin-top: 10px;
}

.d-pad-middle {
    display: flex;
    gap: 40px;
}

.d-pad {
    width: 55px;
    height: 55px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--glass-border);
    color: var(--text-primary);
    font-size: 1.3rem;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.2);
    transition: background 0.1s;
}

.d-pad:active {
    background: rgba(255, 255, 255, 0.2);
    transform: scale(0.95);
}

@media (max-width: 600px) {
    .back-btn {
        top: 1rem;
        left: 1rem;
        padding: 0.5rem 1rem;
        font-size: 0.9rem;
    }

    .grid {
        width: 300px;
        height: 300px;
        gap: 6px;
    }

    .tile {
        font-size: 1.5rem;
    }

    .tile[data-value="128"],
    .tile[data-value="256"],
    .tile[data-value="512"] {
        font-size: 1.3rem;
    }

    .tile[data-value="1024"],
    .tile[data-value="2048"] {
        font-size: 1.1rem;
    }

    .mobile-controls {
        display: flex;
    }

    .game-container {
        padding: 1.5rem;
    }

    .glow-text {
        font-size: 2.2rem;
    }
}