:root {
  --fg: #1b1b1d;
  --fg-muted: #555;
  --bg: #fafafa;
  --card: #fff;
  --border: #e5e5e7;
  --accent: #0a66c2;
  --accent-hover: #0852a0;
  --hero-bg: linear-gradient(180deg, #f4f7fb 0%, #fafafa 100%);
}
@media (prefers-color-scheme: dark) {
  :root {
    --fg: #ececec;
    --fg-muted: #a8a8ad;
    --bg: #111113;
    --card: #1c1c1f;
    --border: #2c2c30;
    --accent: #4ea3ff;
    --accent-hover: #7ebcff;
    --hero-bg: linear-gradient(180deg, #15171c 0%, #111113 100%);
  }
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font: 15px/1.6 -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", Arial, sans-serif;
  color: var(--fg);
  background: var(--bg);
}
a { color: var(--accent); }
a:hover { color: var(--accent-hover); }

/* Top navigation */
.topnav {
  position: sticky;
  top: 0;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  padding: 12px 20px;
  z-index: 20;
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1040px;
  margin: 0 auto;
}
.topnav .brand {
  font-weight: 600;
  color: var(--fg);
  text-decoration: none;
  font-size: 15px;
}
.topnav .links a {
  margin-left: 18px;
  color: var(--fg-muted);
  text-decoration: none;
  font-size: 14px;
}
.topnav .links a:hover { color: var(--accent); }

/* Hero */
.hero {
  background: var(--hero-bg);
  padding: 64px 24px 56px;
  text-align: center;
  border-bottom: 1px solid var(--border);
}
.hero h1 {
  margin: 12px 0 10px;
  font-size: 38px;
  font-weight: 700;
  letter-spacing: -0.02em;
}
.hero .tagline {
  margin: 0 auto 24px;
  max-width: 560px;
  color: var(--fg-muted);
  font-size: 17px;
  line-height: 1.5;
}
.hero .cta {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  padding: 12px 22px;
  border-radius: 10px;
  font-weight: 600;
  text-decoration: none;
  font-size: 15px;
}
.hero .cta:hover { background: var(--accent-hover); color: #fff; }
.hero .cta.disabled {
  background: var(--border);
  color: var(--fg-muted);
  cursor: default;
  pointer-events: none;
}
.hero .sub {
  display: block;
  margin-top: 12px;
  color: var(--fg-muted);
  font-size: 13px;
}

/* Generic content container */
main { max-width: 860px; margin: 0 auto; padding: 0 24px 60px; }
main.narrow { max-width: 760px; }

section {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 32px;
  margin-top: 28px;
}
h2 { margin: 0 0 6px; font-size: 22px; font-weight: 600; letter-spacing: -0.01em; }
h2 + .lastupdated {
  color: var(--fg-muted);
  font-size: 12px;
  margin-bottom: 18px;
}
h3 { margin: 24px 0 6px; font-size: 15px; font-weight: 600; }
p, ul { margin: 8px 0; }
ul { padding-left: 22px; }
li { margin: 3px 0; }
code {
  font: 13px/1.4 ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  background: var(--bg);
  padding: 1px 5px;
  border-radius: 4px;
  border: 1px solid var(--border);
}

/* Feature grid */
.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
  margin-top: 20px;
}
.feature {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 22px;
}
.feature h3 { margin: 0 0 6px; font-size: 16px; }
.feature p { margin: 0; color: var(--fg-muted); font-size: 14px; }

/* Spec list */
.spec {
  display: grid;
  grid-template-columns: 180px 1fr;
  gap: 10px 20px;
  font-size: 14px;
}
.spec dt { color: var(--fg-muted); }
.spec dd { margin: 0; }

/* FAQ */
details {
  border-top: 1px solid var(--border);
  padding: 14px 0;
}
details:first-of-type { border-top: none; }
details > summary {
  cursor: pointer;
  font-weight: 600;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
details > summary::after {
  content: "+";
  color: var(--fg-muted);
  font-weight: 400;
  font-size: 18px;
}
details[open] > summary::after { content: "–"; }
details > p, details > ul { margin-top: 10px; color: var(--fg); }

/* Footer */
footer {
  text-align: center;
  color: var(--fg-muted);
  font-size: 12px;
  padding: 28px 16px 40px;
  border-top: 1px solid var(--border);
  margin-top: 40px;
}
footer a { color: var(--fg-muted); margin: 0 8px; }
footer a:hover { color: var(--accent); }

.muted { color: var(--fg-muted); }
.center { text-align: center; }