:root {
  color-scheme: light;
  --bg: #f6f7f9;
  --card: #ffffff;
  --text: #1f2933;
  --muted: #5b6472;
  --line: #e4e7eb;
  --link: #1f4f82;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}
a { color: var(--link); }
.site-header {
  max-width: 980px;
  margin: 0 auto;
  padding: 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
}
.brand {
  font-weight: 700;
  text-decoration: none;
  color: var(--text);
  letter-spacing: -0.02em;
}
nav {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}
nav a {
  color: var(--muted);
  text-decoration: none;
}
nav a:hover { text-decoration: underline; }
main {
  max-width: 980px;
  margin: 0 auto;
  padding: 24px;
}
.hero {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 44px;
  box-shadow: 0 10px 28px rgba(0,0,0,.05);
}
.hero h1 {
  max-width: 720px;
  margin: 0 0 14px;
  font-size: clamp(32px, 6vw, 56px);
  line-height: 1.05;
  letter-spacing: -0.05em;
}
.hero p {
  max-width: 680px;
  color: var(--muted);
  font-size: 18px;
}
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 16px;
  margin-top: 18px;
}
.cards article, .page {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 28px;
}
.cards h2, .page h1 {
  margin-top: 0;
  letter-spacing: -0.03em;
}
.cards p, .page p {
  color: var(--muted);
}
.note-list {
  padding-left: 20px;
}
footer {
  max-width: 980px;
  margin: 0 auto;
  padding: 24px;
  color: var(--muted);
  font-size: 14px;
}
@media (max-width: 640px) {
  .site-header {
    align-items: flex-start;
    flex-direction: column;
  }
  .hero, .cards article, .page {
    padding: 24px;
  }
}