style.css

h1 {
    text-align: center;
    display: block;
}

#duplicate-button {
    margin: auto;
    color: #fff;
    background: #1565c0;
    border-radius: 100vh;
}

.contain {
    max-width: 730px;
    margin: auto;
    padding-top: 1.5rem;
}