:root {
    --bg-color: #faf8ef;
    --text-color: #776e65;
    --board-bg: #bbada0;
    --cell-bg: #eee4da;
    --tile-colors: {
        2: #eee4da, 4: #ede0c8, 8: #f2b179, 16: #f59563,
        32: #f67c5f, 64: #f65e3b, 128: #edcf72, 256: #edcc61,
        512: #edc850, 1024: #edc53f, 2048: #edc22e, 4096: #3c3a32
    };
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
}

.header {
    width: 100%;
    max-width: 500px;
    display: flex;
    justify-content: space-between;
    margin-bottom: 20px;
}

h1 {
    font-size: 3rem;
    font-weight: bold;
}

.score-container {
    background: var(--board-bg);
    padding: 10px 20px;
    border-radius: 8px;
    text-align: center;
    color: white;
}

.score-title {
    font-size: 0.9rem;
    text-transform: uppercase;
}

.score-value {
    font-size: 1.5rem;
    font-weight: bold;
}

.game-intro {
    margin-bottom: 20px;
    text-align: center;
    line-height: 1.5;
}

.game-container {
    width: 100%;
    max-width: 500px;
    position: relative;
}

.grid-container {
    background: var(--board-bg);
    border-radius: 8px;
    padding: 15px;
    position: relative;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
}

.grid-row {
    display: flex;
    margin-bottom: 15px;
}

.grid-row:last-child {
    margin-bottom: 0;
}

.grid-cell {
    width: 25%;
    height: 0;
    padding-bottom: 25%;
    margin-right: 15px;
    background: rgba(238, 228, 218, 0.35);
    border-radius: 5px;
    position: relative;
}

.grid-cell:last-child {
    margin-right: 0;
}

.tile {
    position: absolute;
    top: 0;
    left: 0;
    width: calc(100% - 15px);
    height: calc(100% - 15px);
    margin: 7.5px;
    border-radius: 5px;
    background: var(--cell-bg);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 2.5rem;
    font-weight: bold;
    color: var(--text-color);
    transition: all 0.1s ease-in-out;
    z-index: 1;
}

@media (max-width: 520px) {
    .tile {
        font-size: 1.8rem;
    }
}

.tile-2 { background-color: #eee4da; }
.tile-4 { background-color: #ede0c8; }
.tile-8 { background-color: #f2b179; color: white; }
.tile-16 { background-color: #f59563; color: white; }
.tile-32 { background-color: #f67c5f; color: white; }
.tile-64 { background-color: #f65e3b; color: white; }
.tile-128 { background-color: #edcf72; color: white; font-size: 2rem; }
.tile-256 { background-color: #edcc61; color: white; font-size: 2rem; }
.tile-512 { background-color: #edc850; color: white; font-size: 2rem; }
.tile-1024 { background-color: #edc53f; color: white; font-size: 1.5rem; }
.tile-2048 { background-color: #edc22e; color: white; font-size: 1.5rem; }
.tile-super { background-color: #3c3a32; color: white; font-size: 1.5rem; }

.tile-new {
    animation: appear 0.2s;
}

.tile-merged {
    animation: pop 0.2s;
}

@keyframes appear {
    0% { transform: scale(0); }
    70% { transform: scale(1.1); }
    100% { transform: scale(1); }
}

@keyframes pop {
    0% { transform: scale(0.9); }
    50% { transform: scale(1.1); }
    100% { transform: scale(1); }
}

.game-message {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(238, 228, 218, 0.73);
    z-index: 100;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    border-radius: 8px;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s;
}

.game-message.game-won, .game-message.game-over {
    opacity: 1;
    pointer-events: auto;
}

.game-message p {
    font-size: 3rem;
    font-weight: bold;
    margin-bottom: 20px;
}

.btn {
    background: #8f7a66;
    color: white;
    border: none;
    border-radius: 5px;
    padding: 10px 20px;
    font-size: 1rem;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.2s;
}

.btn:hover {
    background: #9f8b77;
    transform: translateY(-2px);
}

.btn:active {
    transform: translateY(0);
}

.controls {
    margin-top: 20px;
    display: flex;
    justify-content: space-between;
    width: 100%;
    max-width: 500px;
}

.keyboard-hint {
    margin-top: 30px;
    text-align: center;
    color: #8f7a66;
    font-size: 0.9rem;
}