* {
    box-sizing: border-box;
}

html, body {
    height: 100%;
    overflow: hidden;
    overscroll-behavior: none;
}

body {
    font-family: Arial, sans-serif;
    background: #faf8ef;
    text-align: center;
    margin: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    gap: 8px;
    padding-top: 20px;
    overflow: hidden;
}

h1 {
    margin: 0 0 6px 0;
}

#hud {
    width: min(92vw, 420px);
    margin: 0 auto 10px auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    }

.scores {
    display: flex;
    gap: 10px;
}

.score-box {
    background: #bbada0;
    color: #f9f6f2;
    padding: 8px 12px;
    border-radius: 4px;
    min-width: 90px;
}

.score-box .label {
    font-size: 12px;
    letter-spacing: 1px;
    text-transform: uppercase;
}

.score-box .value {
    font-size: 22px;
    font-weight: bold;
    margin-top: 2px;
}

#restart {
    background: #8f7a66;
    color: #f9f6f2;
    border: none;
    border-radius: 4px;
    padding: 10px 14px;
    font-weight: bold;
    cursor: pointer;
}

#restart:hover {
    background: #9f8b76;
}

#game {
    position: relative;
    width: min(100vw, 420px);
    margin: 0 auto;
    touch-action: none;
    overscroll-behavior: none;
}

#grid {
    width: 100%;
    aspect-ratio: 1 / 1;
    margin: 10px auto 0 auto;
    background: #bbada0;
    padding: 10px;
    border-radius: 5px;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    position: relative;
    overflow: hidden;
}

.tiles {
    position: absolute;
    inset: 0;
    pointer-events: none;
    z-index: 1;
}

.message {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(238, 228, 218, 0.8);
    color: #776e65;
    font-size: 24px;
    font-weight: bold;
    border-radius: 5px;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s ease-in-out;
    z-index: 2;
}

.message.show {
    opacity: 1;
    pointer-events: auto;
}

@media (max-width: 520px) {
    body {
        padding-top: 10px;
    }
    #hud {
        flex-direction: column;
        align-items: stretch;
    }
    .scores {
        justify-content: center;
    }
    #restart {
        width: 100%;
    }
}

.cell {
    width: 100%;
    height: 100%;
    background: #cdc1b4;
    border-radius: 3px;
}

.tile {
    position: absolute;
    width: 70px;
    height: 70px;
    line-height: 70px;
    border-radius: 3px;
    font-size: 24px;
    font-weight: bold;
    background: #eee4da;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: transform 0.18s ease-in-out;
    transform: translate(var(--x, 0px), var(--y, 0px)) scale(1);
}

.tile-2 {
    background: #eee4da;
    color: #776e65;
}

.tile-4 {
    background: #ede0c8;
    color: #776e65;
}

.tile-8 {
    background: #f2b179;
    color: #f9f6f2;
}

.tile-16 {
    background: #f59563;
    color: #f9f6f2;
}

.tile-32 {
    background: #f67c5f;
    color: #f9f6f2;
}

.tile-64 {
    background: #f65e3b;
    color: #f9f6f2;
}

.tile-128 {
    background: #edcf72;
    color: #f9f6f2;
    font-size: 28px;
}

.tile-256 {
    background: #edcc61;
    color: #f9f6f2;
    font-size: 28px;
}

.tile-512 {
    background: #edc850;
    color: #f9f6f2;
    font-size: 28px;
}

.tile-1024 {
    background: #edc53f;
    color: #f9f6f2;
    font-size: 22px;
}

.tile-2048 {
    background: #edc22e;
    color: #f9f6f2;
    font-size: 22px;
}

.tile-super {
    background: #3c3a32;
    color: #f9f6f2;
    font-size: 20px;
}

.tile.new {
    animation: pop 0.2s ease-out;
}

.tile.merge {
    animation: pop 0.22s ease-in-out 0.18s forwards;
}

@keyframes pop {
    0% { transform: translate(var(--x, 0px), var(--y, 0px)) scale(0.6); }
    60% { transform: translate(var(--x, 0px), var(--y, 0px)) scale(1.1); }
    100% { transform: translate(var(--x, 0px), var(--y, 0px)) scale(1); }
}