toychain/style.css

body {
  background-color: #400244;
}
body > div:first-child {
  background-color: #fdfcff;
  max-width: 720px;
  margin: auto;
  padding: 0.7rem;
  opacity: 0.99;
}
div#nav {
  position: fixed;
  top: 0;
  right: 0;
}

textarea {
  width: calc(100% - 1rem);
}