body {
    background: #0d1117;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    color: white;
    font-family: sans-serif;
}

.card {
    background: #161b22;
    padding: 2rem;
    border-radius: 15px;
    border: 1px solid #30363d;
    text-align: center;
    box-shadow: 0 4px 20px rgba(0,0,0,0.8);
}

h1 { color: #58a6ff; }

button {
    background: #238636;
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 5px;
    cursor: pointer;
    font-weight: bold;
}

button:hover { background: #2ea043; }