* {
    box-sizing: border-box;
}

body {
    font-family: Arial, sans-serif;
    background-color: #f4f4f4;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}

.game-container {
    text-align: center;
}

.game-board {
    display: grid;
    grid-template-columns: repeat(4, 100px);
    grid-gap: 10px;
    margin-top: 20px;
}

.card {
    width: 100px;
    height: 100px;
    background-color: #ddd;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 24px;
    cursor: pointer;
    border-radius: 10px;
    user-select: none;
}

.card.flipped {
    background-color: #fff;
    cursor: default;
}

.card.matched {
    background-color: #8BC34A;
    cursor: default;
}

button {
    padding: 10px 20px;
    font-size: 16px;
    cursor: pointer;
    border: none;
    border-radius: 5px;
    background-color: #2196F3;
    color: white;
}

button:hover {
    background-color: #1976D2;
}

h1 {
    margin: 0;
}

.scoreboard {
    margin-top: 20px;
    font-size: 18px;
}

.hidden {
    visibility: hidden;
}