*:root {
  --max: 980px;
  --pad: 16px;
  --radius: 14px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  line-height: 1.35;
  color: #111;
  background: #f7f7f7;
}

header {
  border-bottom: 1px solid #e9e9e9;
  background: #fff;
  position: sticky;
  top: 0;
  z-index: 10;
}

.wrap {
  max-width: var(--max);
  margin: 0 auto;
  padding: var(--pad);
}

nav a {
  margin-right: 12px;
  text-decoration: none;
  color: #111;
  font-weight: 500;
}

nav a:hover {
  text-decoration: underline;
}

h1 {
  font-size: 28px;
  margin: 12px 0 6px;
}

h2 {
  font-size: 20px;
  margin: 18px 0 8px;
}

h3 {
  margin: 0 0 6px;
}

p {
  margin: 10px 0;
}

.card {
  border: 1px solid #e9e9e9;
  border-radius: var(--radius);
  padding: 14px;
  background: #fff;
}

.grid {
  display: grid;
  gap: 12px;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

label {
  display: block;
  font-size: 13px;
  margin: 10px 0 6px;
  color: #333;
}

input,
select,
button,
textarea {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid #ddd;
  border-radius: 12px;
  font-size: 14px;
}

button {
  cursor: pointer;
  border: 1px solid #111;
  background: #111;
  color: #fff;
  margin-top: 10px;
}

button.secondary {
  background: #fff;
  color: #111;
}

.muted {
  color: #666;
  font-size: 13px;
}

.result {
  font-weight: 700;
  font-size: 22px;
  margin-top: 10px;
}

.badge {
  display: inline-block;
  padding: 6px 10px;
  border-radius: 999px;
  border: 1px solid #e9e9e9;
  font-size: 12px;
  margin-right: 6px;
  background: #fafafa;
}

.ad {
  border: 1px dashed #bbb;
  border-radius: var(--radius);
  padding: 12px;
  background: #fafafa;
  margin: 12px 0;
  text-align: center;
  font-size: 13px;
  color: #666;
}

footer {
  border-top: 1px solid #e9e9e9;
  margin-top: 22px;
  background: #fff;
}

small {
  color: #666;
}

ul {
  margin: 8px 0 0 18px;
}

pre {
  white-space: pre-wrap;
}