body {
    font-family: Arial, sans-serif;
    background-color: #f0f0f0;
    padding: 20px;
}

.back-link {
    position: absolute;
    top: 20px;
    left: 20px;
    color: #333;
    text-decoration: none;
    font-weight: 500;
    padding: 8px 12px;
    border-radius: 6px;
    background: white;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.back-link:hover {
    background: #eee;
}

.container {
    width: 100%;
    max-width: 800px;
    margin: 0 auto;
}

h1 {
    color: #333;
    margin-bottom: 20px;
    text-align: center;
}

button {
    padding: 10px 20px;
    font-size: 14px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    background-color: #f44336;
    color: #fff;
    display: block;
    margin: 0 auto 20px;
}

button:hover {
    background-color: #da190b;
}

canvas {
    background: #fff;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    cursor: crosshair;
    display: block;
    margin: 0 auto;
}

.hint {
    color: #666;
    margin-top: 15px;
    font-size: 14px;
    text-align: center;
}