:root {
  --color-canvas: #f5f5f7;
  --color-surface: #fff;
  --color-ink: #1d1d1f;
  --color-text-secondary: #626269;
  --color-border: #dadae0;
  --color-primary: #0066cc;
  --color-error: #b42318;
  --color-success: #247346;
}
* {
  box-sizing: border-box;
}
body {
  margin: 0;
  background: var(--color-canvas);
  color: var(--color-ink);
  font:
    17px/26px system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "PingFang SC",
    sans-serif;
}
main {
  max-width: 1120px;
  margin: 40px auto;
  padding: 24px;
}
h1,
h2 {
  line-height: 1.3;
  font-weight: 600;
}
h1 {
  font-size: 32px;
}
h2 {
  font-size: 22px;
}
p,
li {
  max-width: 76ch;
}
a {
  color: var(--color-primary);
}
nav {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
  margin-bottom: 32px;
}
.grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}
.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 16px;
  padding: 24px;
  margin: 16px 0;
}
label {
  display: block;
  margin: 16px 0 8px;
}
input,
button {
  font: inherit;
  border-radius: 12px;
  min-height: 44px;
  padding: 12px 16px;
  border: 1px solid var(--color-border);
}
input {
  width: 100%;
  background: var(--color-surface);
  color: var(--color-ink);
}
button {
  background: var(--color-primary);
  color: white;
  cursor: pointer;
  margin: 16px 8px 8px 0;
}
button:disabled {
  opacity: 0.5;
  cursor: default;
}
pre {
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  font-size: 14px;
}
small {
  color: var(--color-text-secondary);
}
#message {
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}
input:focus,
button:focus,
a:focus {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
}
@media (max-width: 800px) {
  main {
    padding: 16px;
    margin: 20px auto;
  }
  .grid {
    grid-template-columns: 1fr;
  }
}