html, body { margin: 0; }
body {
  background: #fff;
  color: #111;
  font: 17px/1.55 "Segoe UI", Tahoma, sans-serif;
}
main {
  max-width: 32rem;
  margin: 0 auto;
  padding: 6rem 1.25rem;
}
h1 { font-weight: 600; font-size: 1.6rem; margin: 0 0 0.5rem; }
p { color: #555; }
textarea, input {
  width: 100%;
  font: inherit;
  border: 1px solid #111;
  padding: 0.7rem;
  margin: 0.4rem 0 0.8rem;
}
button {
  font: inherit;
  background: #111;
  color: #fff;
  border: 0;
  padding: 0.55rem 1rem;
  cursor: pointer;
}
.warn { color: #8a2a1a; font-size: 0.9rem; }
pre { white-space: pre-wrap; word-break: break-word; }
#err { color: #8a2a1a; }
#ok input { width: auto; flex: 1; }
#ok { display: flex; gap: 0.4rem; align-items: center; }
#ok[hidden] { display: none; }