:root {
  --bg: #0b1020;
  --bg-soft: #121a33;
  --card: rgba(255, 255, 255, 0.04);
  --line: rgba(255, 255, 255, 0.08);
  --text: #e8edf7;
  --muted: #9aa7c0;
  --accent: #6ea8fe;
  --accent-2: #8b5cf6;
  --radius: 16px;
  --shadow: 0 10px 40px rgba(0, 0, 0, 0.25);
  --font: "Segoe UI", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font);
  color: var(--text);
  background: var(--bg);
  line-height: 1.65;
}

.bg {
  position: fixed;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(900px 500px at 15% -10%, rgba(110, 168, 254, 0.18), transparent 60%),
    radial-gradient(700px 420px at 90% 10%, rgba(139, 92, 246, 0.16), transparent 55%),
    linear-gradient(180deg, var(--bg), var(--bg-soft));
}

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

a:hover {
  text-decoration: underline;
}

code {
  padding: 0.1em 0.4em;
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.08);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.92em;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1rem 1.5rem;
  backdrop-filter: blur(12px);
  background: rgba(11, 16, 32, 0.7);
  border-bottom: 1px solid var(--line);
}

.logo {
  font-weight: 700;
  font-size: 1.15rem;
  letter-spacing: 0.02em;
  color: var(--text);
  text-decoration: none;
}

.logo span {
  color: var(--accent);
}

.nav {
  display: flex;
  gap: 1.1rem;
  flex-wrap: wrap;
}

.nav a {
  color: var(--muted);
  font-size: 0.95rem;
  text-decoration: none;
}

.nav a:hover {
  color: var(--text);
}

main {
  width: min(880px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 2.5rem 0 4rem;
}

.hero {
  padding: 1.5rem 0 2rem;
}

.eyebrow {
  margin: 0 0 0.6rem;
  color: var(--accent);
  font-size: 0.85rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.hero h1 {
  margin: 0 0 0.9rem;
  font-size: clamp(1.8rem, 4vw, 2.5rem);
  line-height: 1.25;
  font-weight: 700;
}

.hl {
  background: linear-gradient(120deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.lead {
  margin: 0 0 1.4rem;
  max-width: 40rem;
  color: var(--muted);
  font-size: 1.05rem;
}

.hero-actions {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 2.6rem;
  padding: 0.55rem 1.15rem;
  border-radius: 999px;
  border: 1px solid transparent;
  font-size: 0.95rem;
  text-decoration: none;
  transition: transform 0.15s ease, background 0.15s ease, border-color 0.15s ease;
}

.btn:hover {
  transform: translateY(-1px);
  text-decoration: none;
}

.btn.primary {
  color: #0b1020;
  background: linear-gradient(120deg, var(--accent), #93c5fd);
}

.btn.ghost {
  color: var(--text);
  border-color: var(--line);
  background: rgba(255, 255, 255, 0.03);
}

.btn.ghost:hover {
  border-color: rgba(255, 255, 255, 0.2);
}

.card {
  margin-top: 1.25rem;
  padding: 1.4rem 1.5rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card);
  box-shadow: var(--shadow);
}

.card h2 {
  margin: 0 0 0.75rem;
  font-size: 1.25rem;
}

.card p {
  margin: 0 0 0.75rem;
  color: var(--muted);
}

.meta-list {
  list-style: none;
  margin: 0.75rem 0 0;
  padding: 0;
}

.meta-list li {
  display: flex;
  gap: 0.75rem;
  padding: 0.45rem 0;
  border-top: 1px solid var(--line);
  color: var(--text);
  font-size: 0.95rem;
}

.meta-list li span:first-child {
  flex: 0 0 4.5rem;
  color: var(--muted);
}

.notes {
  display: grid;
  gap: 0.85rem;
}

@media (min-width: 720px) {
  .notes {
    grid-template-columns: repeat(3, 1fr);
  }
}

.note {
  padding: 1rem;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.025);
}

.note h3 {
  margin: 0 0 0.45rem;
  font-size: 1rem;
}

.note p {
  margin: 0;
  font-size: 0.92rem;
}

.muted {
  color: var(--muted);
}

.site-footer {
  width: min(880px, calc(100% - 2rem));
  margin: 0 auto 2.5rem;
  padding-top: 1rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.88rem;
}

.site-footer p {
  margin: 0.25rem 0;
}

.fine {
  font-size: 0.8rem;
  opacity: 0.85;
}