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

body {
    font-family: 'Arial', sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background: linear-gradient(135deg, #f6d365 0%, #fda085 100%);
}

.game-container {
    text-align: center;
    position: relative;
    background: #ffffff;
    border-radius: 15px;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
    padding: 30px;
    width: 400px;
    max-width: 90%;
}

.header {
    margin-bottom: 20px;
}

.header h1 {
    font-size: 2.5rem;
    color: #333;
}

.controls {
    display: flex;
    justify-content: space-around;
    margin-bottom: 20px;
    color: #555;
}

.grid {
    display: grid;
    grid-template-columns: repeat(4, 80px);
    grid-template-rows: repeat(4, 80px);
    gap: 5px;
    margin: 0 auto;
    background: #eee;
    border-radius: 10px;
    padding: 5px;
    transition: opacity 0.5s, transform 0.5s;
}

.grid.active {
    opacity: 1;
    transform: scale(1);
}

.tile {
    background-color: #4a90e2;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 24px;
    color: #fff;
    font-weight: bold;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.3s, transform 0.3s;
}

.tile.empty {
    background-color: transparent;
    cursor: default;
}

.tile:hover {
    background-color: #357ABD;
}

.btn {
    padding: 12px 24px;
    font-size: 18px;
    cursor: pointer;
    color: #fff;
    border: none;
    border-radius: 8px;
    transition: background-color 0.3s, transform 0.3s;
}

.btn-start {
    background-color: #4a90e2;
}

.btn-start:hover {
    background-color: #357ABD;
}

.btn-retry {
    background-color: #e94e77;
}

.btn-retry:hover {
    background-color: #d43f5e;
}

.btn-mute {
    background-color: #7f8c8d;
}

.btn-mute:hover {
    background-color: #6c757d;
}

.hidden {
    display: none;
}

.game-over {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: #ffffff;
    border-radius: 15px;
    padding: 20px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
}

.game-over h2 {
    margin-bottom: 20px;
    color: #333;
}