:root {
  --accent: #2E8FE6;
  --grad-start: #2E90E6;
  --grad-end: #27C7C4;
  --bg: #EDF5FB;
  --text: #1D3A55;
  --text-strong: #274660;
  --text-muted: #6B8299;
  --card: #FFFFFF;
  --border: #E1EBF3;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 32px 16px 64px;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

.page {
  max-width: 760px;
  margin: 0 auto;
  background: var(--card);
  border-radius: 20px;
  box-shadow: 0 12px 40px rgba(46, 143, 230, 0.12);
  overflow: hidden;
}

.hero {
  background: linear-gradient(135deg, var(--grad-start), var(--grad-end));
  color: #fff;
  padding: 40px 40px 36px;
}

.hero .app-name {
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  opacity: 0.9;
  margin: 0 0 8px;
}

.hero h1 {
  margin: 0;
  font-size: 30px;
  font-weight: 700;
}

.hero .updated {
  margin: 14px 0 0;
  font-size: 14px;
  opacity: 0.9;
}

.content {
  padding: 32px 40px 40px;
}

.intro {
  color: var(--text-muted);
  margin: 0 0 28px;
}

.toc {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 20px 24px;
  margin: 0 0 36px;
}

.toc h2 {
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin: 0 0 12px;
}

.toc ol {
  margin: 0;
  padding-left: 20px;
  columns: 2;
  column-gap: 32px;
}

.toc li {
  margin-bottom: 6px;
  break-inside: avoid;
}

.toc a {
  color: var(--accent);
  text-decoration: none;
}

.toc a:hover {
  text-decoration: underline;
}

section {
  margin: 0 0 32px;
  scroll-margin-top: 24px;
}

section h2 {
  font-size: 20px;
  font-weight: 700;
  color: var(--text-strong);
  margin: 0 0 10px;
}

section p {
  margin: 0 0 12px;
}

section ul {
  margin: 0 0 12px;
  padding-left: 22px;
}

section li {
  margin-bottom: 6px;
}

a {
  color: var(--accent);
}

.footer {
  border-top: 1px solid var(--border);
  padding: 24px 40px 32px;
  color: var(--text-muted);
  font-size: 14px;
}

.footer a {
  color: var(--accent);
  text-decoration: none;
}

.footer a:hover {
  text-decoration: underline;
}

/* Landing page */
.hero.landing {
  text-align: center;
  padding: 56px 40px 52px;
}

.hero .tagline {
  margin: 14px 0 0;
  font-size: 17px;
  font-weight: 500;
  opacity: 0.95;
}

.hero .lead {
  margin: 14px auto 0;
  max-width: 520px;
  font-size: 15px;
  opacity: 0.9;
}

.cta-row {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
  margin-top: 28px;
}

.btn {
  display: inline-block;
  padding: 11px 22px;
  border-radius: 999px;
  font-size: 15px;
  font-weight: 600;
  text-decoration: none;
  border: 1px solid rgba(255, 255, 255, 0.6);
  color: #fff;
}

.btn.primary {
  background: #fff;
  color: var(--accent);
  border-color: #fff;
}

.features {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin: 8px 0 12px;
}

.feature {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 22px 20px;
}

.feature h3 {
  margin: 0 0 8px;
  font-size: 17px;
  color: var(--text-strong);
}

.feature p {
  margin: 0;
  font-size: 14px;
  color: var(--text-muted);
}

/* 404 page */
.notfound {
  text-align: center;
  padding: 72px 40px;
}

.notfound .code {
  font-size: 72px;
  font-weight: 800;
  line-height: 1;
  background: linear-gradient(135deg, var(--grad-start), var(--grad-end));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.notfound h1 {
  margin: 16px 0 8px;
  font-size: 24px;
  color: var(--text-strong);
}

.notfound p {
  margin: 0 0 28px;
  color: var(--text-muted);
}

@media (max-width: 560px) {
  .features {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 560px) {
  .hero,
  .content,
  .footer {
    padding-left: 22px;
    padding-right: 22px;
  }
  .hero h1 {
    font-size: 25px;
  }
  .toc ol {
    columns: 1;
  }
}