* {
  box-sizing: border-box;
}
html,
body {
  margin: 0;
  padding: 0;
  font-family:
    -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue",
    Arial, sans-serif;
  font-size: 16px;
  line-height: 1.4;
}
main {
  max-width: 720px;
  margin: 0 auto;
  padding: 24px 16px 48px;
}
h1 {
  margin: 0 0 12px;
  font-size: 24px;
}
h2,
h3 {
  margin: 16px 0 8px;
}
.hint {
  color: #64748b;
  margin: 0 0 24px;
}
button {
  display: block;
  width: 100%;
  padding: 16px;
  font-size: 18px;
  border: 0;
  border-radius: 12px;
  background: #3b82f6;
  color: #fff;
  cursor: pointer;
}
button:active {
  opacity: 0.85;
}
section {
  margin-top: 24px;
}
#meter {
  width: 100%;
  max-width: 600px;
  height: 80px;
  background: #e2e8f0;
  border-radius: 8px;
  display: block;
}
pre {
  white-space: pre-wrap;
  word-break: break-word;
  background: #0f172a;
  color: #e2e8f0;
  padding: 12px;
  border-radius: 8px;
  font-size: 12px;
  max-height: 320px;
  overflow: auto;
}
#error pre {
  background: #7f1d1d;
}