body {
    background: #111;
    color: #fff;
    font-family: 'Courier New', Courier, monospace;
    text-align: center;
}

.back-btn {
    display: inline-block;
    margin-top: 20px;
    margin-bottom: 10px;
    padding: 8px 18px;
    background: #222;
    color: #0ff;
    border: 2px solid #0ff;
    border-radius: 6px;
    text-decoration: none;
    font-family: inherit;
    font-size: 1em;
    letter-spacing: 1px;
    box-shadow: 0 0 8px #0ff;
    transition: background 0.2s, color 0.2s;
}

.back-btn:hover {
    background: #0ff;
    color: #222;
}

h1 {
    margin-top: 20px;
    font-size: 2em;
    letter-spacing: 2px;
}

canvas {
    background: #222;
    display: block;
    margin: 20px auto;
    border: 2px solid #fff;
    box-shadow: 0 0 20px #0ff;
}