/* Dark is the default theme (also the fallback before the toggle script runs). */
:root, :root[data-theme="dark"] {
  --bg: #0d0d1c;
  --bg2: #14142b;
  --fg: #f5f5fa;
  --muted: #a9a9c4;
  --accent: #5b6bff;
  --accent2: #7c8cff;
  --card: rgba(255, 255, 255, 0.05);
  --border: rgba(255, 255, 255, 0.09);
  --nav-bg: rgba(13, 13, 28, 0.85);
  --hero-top: #2a2a52;
}

/* Light tokens. */
:root[data-theme="light"] {
  --bg: #ffffff;
  --bg2: #f4f5fb;
  --fg: #14142b;
  --muted: #55556e;
  --accent: #4a5bff;
  --accent2: #3a4be0;
  --card: rgba(20, 20, 43, 0.035);
  --border: rgba(20, 20, 43, 0.12);
  --nav-bg: rgba(255, 255, 255, 0.85);
  --hero-top: #dfe3ff;
}

/* System (no explicit choice): follow the OS preference. */
@media (prefers-color-scheme: light) {
  :root:not([data-theme]) {
    --bg: #ffffff;
    --bg2: #f4f5fb;
    --fg: #14142b;
    --muted: #55556e;
    --accent: #4a5bff;
    --accent2: #3a4be0;
    --card: rgba(20, 20, 43, 0.035);
    --border: rgba(20, 20, 43, 0.12);
    --nav-bg: rgba(255, 255, 255, 0.85);
    --hero-top: #dfe3ff;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
  color: var(--fg);
  background: var(--bg);
  line-height: 1.6;
}

a { color: var(--accent2); text-decoration: none; }
a:hover { text-decoration: underline; }

.wrap { max-width: 1040px; margin: 0 auto; padding: 0 24px; }

/* Nav */
.nav {
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: var(--nav-bg);
  backdrop-filter: blur(8px);
}
.nav .wrap { display: flex; align-items: center; justify-content: space-between; height: 60px; }
.brand { display: inline-flex; align-items: center; gap: 9px; font-weight: 700; color: var(--fg); font-size: 18px; }
.brand img { display: block; width: 28px; height: 28px; }
.brand:hover { text-decoration: none; }
.nav nav { display: inline-flex; align-items: center; }
.nav nav a { margin-left: 22px; color: var(--muted); }
.nav nav a:hover { color: var(--fg); text-decoration: none; }
.theme-toggle {
  margin-left: 22px;
  padding: 6px 12px;
  font: inherit;
  font-size: 14px;
  color: var(--muted);
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 999px;
  cursor: pointer;
}
.theme-toggle:hover { color: var(--fg); border-color: var(--accent2); }

/* Hero */
.hero {
  text-align: center;
  padding: 110px 0 90px;
  background: radial-gradient(120% 90% at 50% 0%, var(--hero-top) 0%, var(--bg2) 55%, var(--bg) 100%);
}
.hero h1 {
  font-size: clamp(32px, 5vw, 54px);
  line-height: 1.1;
  margin: 0 auto 20px;
  max-width: 760px;
  letter-spacing: -0.5px;
}
.lead { color: var(--muted); font-size: 19px; max-width: 640px; margin: 0 auto 34px; }
.cta { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }
.btn {
  display: inline-block;
  padding: 13px 24px;
  border-radius: 12px;
  font-weight: 600;
  font-size: 16px;
}
.btn.primary { background: var(--accent); color: #fff; }
.btn.primary:hover { background: var(--accent2); text-decoration: none; }
.btn.ghost { border: 1px solid var(--border); color: var(--fg); }
.btn.ghost:hover { border-color: var(--accent2); text-decoration: none; }

/* Sections */
section { padding: 64px 0; }
section h2 { font-size: 28px; margin: 0 0 28px; text-align: center; }

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
}
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 24px;
}
.card .icon { font-size: 28px; margin-bottom: 10px; }
.card h3 { margin: 0 0 8px; font-size: 18px; }
.card p { color: var(--muted); margin: 0; }
.card.link { display: block; color: var(--fg); transition: border-color 0.15s, transform 0.1s; }
.card.link:hover { border-color: var(--accent2); transform: translateY(-2px); text-decoration: none; }
.card.link h3 { color: var(--accent2); font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 15px; }

/* How */
.how ol { max-width: 720px; margin: 0 auto; padding-left: 22px; }
.how li { margin-bottom: 12px; color: var(--muted); }
.how li strong { color: var(--fg); }

footer {
  border-top: 1px solid var(--border);
  padding: 30px 0;
  text-align: center;
  color: var(--muted);
}
footer p { margin: 0; }