* { box-sizing: border-box; }

:root {
  --bg-top: #cdeaf8;
  --bg-bottom: #f4f8fb;
  --text: #1a2531;
  --text-muted: #5b6a78;
  --accent: #4a8fd4;
  --card: #ffffff;
  --card-border: #e2eaf2;
  --max-width: 680px;
  --radius: 16px;
}

html, body { margin: 0; padding: 0; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Rounded", "SF Pro Text",
               "Segoe UI", system-ui, sans-serif;
  background: linear-gradient(180deg, var(--bg-top) 0%, var(--bg-bottom) 35%);
  color: var(--text);
  line-height: 1.65;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

header, main, footer {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

header { padding-top: 56px; padding-bottom: 8px; }
main { padding-top: 16px; padding-bottom: 80px; }
footer {
  padding-top: 56px;
  padding-bottom: 48px;
  color: var(--text-muted);
  font-size: 13px;
  text-align: center;
}

h1 { font-size: 36px; font-weight: 700; margin: 0 0 8px; letter-spacing: -0.5px; }
h2 { font-size: 22px; font-weight: 600; margin: 40px 0 12px; }
p { margin: 12px 0; }
ul, ol { padding-left: 22px; margin: 12px 0; }
li { margin-bottom: 6px; }

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

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
nav a { display: inline-block; margin-bottom: 12px; font-weight: 500; }

details {
  margin-bottom: 12px;
  padding: 16px 18px;
  background: var(--card);
  border-radius: var(--radius);
  border: 1px solid var(--card-border);
}
details summary {
  cursor: pointer;
  font-weight: 600;
  list-style: none;
  padding-right: 24px;
  position: relative;
}
details summary::after {
  content: "+";
  position: absolute;
  right: 0;
  top: 0;
  color: var(--accent);
  font-weight: 700;
  font-size: 18px;
}
details[open] summary::after { content: "−"; }
details[open] summary { margin-bottom: 12px; }

.big-link {
  display: inline-block;
  font-size: 20px;
  font-weight: 600;
  padding: 14px 24px;
  background: var(--card);
  border-radius: 999px;
  border: 1px solid var(--card-border);
  margin: 8px 0;
}

/* Landing page hero */
.hero header { display: none; }
.hero main {
  min-height: 90vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
}
.hero h1 { font-size: 64px; margin-top: 0; }
.hero .tagline { font-size: 22px; color: var(--text-muted); margin-bottom: 32px; }
.hero .links {
  display: flex;
  gap: 12px;
  margin-top: 24px;
  flex-wrap: wrap;
  justify-content: center;
}
.hero .links a {
  padding: 12px 22px;
  background: var(--card);
  border-radius: 999px;
  border: 1px solid var(--card-border);
  font-weight: 500;
  color: var(--text);
}
.hero .links a:hover { background: var(--accent); color: white; text-decoration: none; border-color: var(--accent); }

@media (max-width: 480px) {
  header { padding-top: 36px; }
  h1 { font-size: 28px; }
  .hero h1 { font-size: 44px; }
  .hero .tagline { font-size: 18px; }
}