style.css

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

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

.contain { 
  max-width: 900px; 
  margin: auto; 
  padding-top: 1.5rem;
}