:root {
    --snap-duration: 148ms;
    --snap-easing: cubic-bezier(0.2, 0.8, 0.2, 1);
    --grid-cell-size: 80px;
    --grid-gap: 4px;
}

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

html, body {
    width: 100%;
    height: 100%;
    overflow: hidden;
}

body {
    background: #0a0a0f;
    display: flex;
    justify-content: center;
    align-items: center;
    font-family: 'SF Mono', 'Fira Code', monospace;
}

#app {
    position: relative;
}

.snapper {
    position: absolute;
    top: 0;
    left: 0;
    width: 18px;
    height: 18px;
    margin: -9px 0 0 -9px;
    pointer-events: none;
    transition: transform var(--snap-duration) var(--snap-easing);
}

.snapper-dot {
    width: 100%;
    height: 100%;
    border-radius: 999px;
    background: #00ffcc;
    box-shadow: 0 0 18px rgba(0, 255, 204, 0.45);
}

#snap-grid {
    display: grid;
    grid-template-columns: repeat(3, var(--grid-cell-size));
    grid-template-rows: repeat(3, var(--grid-cell-size));
    gap: var(--grid-gap);
}

.snap-cell {
    width: var(--grid-cell-size);
    height: var(--grid-cell-size);
    background: #12121a;
    border: 1px solid #1a1a2a;
    border-radius: 4px;
    cursor: pointer;
    position: relative;
    transform: translate3d(0, 0, 0);
    transition: transform var(--snap-duration) var(--snap-easing);
    will-change: transform;
}

.snap-cell::after {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: 4px;
    background: transparent;
    transition: background var(--snap-duration) var(--snap-easing);
    pointer-events: none;
}

.snap-cell:hover {
    border-color: #2a2a4a;
    background: #16162a;
}

.snap-cell:active {
    border-color: #00ffcc;
    transform: scale(0.96);
}

.snap-cell.snapped {
    background: #0d1f3f;
    border-color: #00ffcc;
    box-shadow:
        0 0 8px rgba(0, 255, 204, 0.3),
        inset 0 0 4px rgba(0, 255, 204, 0.1);
}

.snap-cell.snapped::after {
    background: radial-gradient(circle at center, rgba(0, 255, 204, 0.08), transparent 70%);
}

.snap-cell.snap-animating {
    animation: snap-in var(--snap-duration) var(--snap-easing);
}

@keyframes snap-in {
    0% {
        transform: scale(0.85);
        opacity: 0.3;
    }
    40% {
        transform: scale(1.04);
        opacity: 0.8;
    }
    100% {
        transform: scale(1);
        opacity: 1;
    }
}