body{background-color:#00f;display:flex;justify-content:center;align-items:center;height:100vh;margin:0;font-family:Arial,sans-serif}.game-board{display:grid;grid-template-columns:repeat(4,100px);grid-gap:10px}.card{width:100px;height:100px;background-color:#fff;display:flex;justify-content:center;align-items:center;font-size:2rem;cursor:pointer;border-radius:8px;box-shadow:0 4px 8px #0003}.flipped{background-color:#f0f0f0}