:root {
  --ink: #171a22;
  --night: #090b10;
  --slate: #343b48;
  --fog: #e9edf1;
  --paper: #f8fafc;
  --blue: #2d68d7;
  --amber: #e8a634;
  --muted: #687181;
  --line: rgba(23, 26, 34, 0.13);
  --serif: "Iowan Old Style", "Palatino Linotype", "Book Antiqua", Palatino, "Songti SC", STSong, Georgia, serif;
  --sans: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", sans-serif;
  --mono: ui-monospace, "SFMono-Regular", Menlo, monospace;
  color: var(--ink);
  background: var(--fog);
  font-family: var(--serif);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-width: 320px;
  background:
    radial-gradient(circle at 8% 0%, rgba(45, 104, 215, 0.13), transparent 31rem),
    radial-gradient(circle at 92% 12%, rgba(232, 166, 52, 0.13), transparent 26rem),
    var(--fog);
}

a { color: inherit; }
img, video { max-width: 100%; }

.shell { width: min(1080px, calc(100% - 32px)); margin: 0 auto; padding: 18px 0 72px; }
.island {
  position: sticky;
  z-index: 10;
  top: 12px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 58px;
  padding: 9px 12px 9px 16px;
  color: #fff;
  background: rgba(9, 11, 16, 0.95);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 21px;
  box-shadow: 0 18px 44px rgba(15, 20, 31, 0.18);
  backdrop-filter: blur(20px) saturate(1.3);
  font-family: var(--sans);
}

.brand { display: flex; align-items: center; gap: 10px; font-weight: 750; text-decoration: none; }
.brand img { width: 32px; height: 32px; object-fit: contain; }
.nav-actions { display: flex; align-items: center; gap: 18px; font-size: 13px; }
.nav-actions a { color: rgba(255, 255, 255, 0.68); text-decoration: none; }
.nav-actions a:hover { color: #fff; }
.nav-actions .download { padding: 9px 13px; color: #11151d; font-weight: 760; background: #fff; border-radius: 11px; }

.hero { padding: 94px 52px 70px; }
.eyebrow, .kicker {
  margin: 0 0 18px;
  color: var(--blue);
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 780;
  letter-spacing: 0.095em;
  text-transform: uppercase;
}

h1 { max-width: 880px; margin: 0; font-size: clamp(54px, 8vw, 96px); font-weight: 590; letter-spacing: -0.058em; line-height: 0.94; }
.lead { max-width: 760px; margin: 28px 0 0; color: var(--slate); font-size: clamp(20px, 2.7vw, 28px); line-height: 1.42; }
.lead [lang="zh-CN"] { display: block; margin-top: 12px; color: var(--muted); font-size: 0.7em; line-height: 1.58; }

.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 32px; font-family: var(--sans); }
.button { display: inline-flex; align-items: center; min-height: 46px; padding: 0 17px; font-weight: 740; text-decoration: none; border-radius: 13px; }
.button-primary { color: #fff; background: var(--blue); }
.button-secondary { background: rgba(248, 250, 252, 0.78); border: 1px solid var(--line); }

.proof {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, 0.76fr);
  gap: 40px;
  align-items: center;
  margin: 0 0 72px;
  padding: 32px;
  background: var(--night);
  border-radius: 30px;
  color: #fff;
}

.proof img { width: 100%; border-radius: 18px; box-shadow: 0 20px 44px rgba(0, 0, 0, 0.24); }
.proof h2 { margin: 0; font-size: clamp(34px, 5vw, 56px); line-height: 1; }
.proof p { color: rgba(255, 255, 255, 0.68); font-family: var(--sans); line-height: 1.65; }

.article { max-width: 820px; margin: 0 auto; }
.article section { margin: 0 0 66px; }
.article h2 { margin: 0 0 18px; font-size: clamp(36px, 5vw, 52px); letter-spacing: -0.045em; line-height: 1.02; }
.article h3 { margin: 30px 0 10px; font-size: 25px; }
.article p, .article li { color: var(--slate); font-family: var(--sans); font-size: 17px; line-height: 1.72; }
.article ul, .article ol { padding-left: 1.3em; }
.article li + li { margin-top: 8px; }
.article strong { color: var(--ink); }
.zh { padding: 22px 24px; background: rgba(248, 250, 252, 0.72); border: 1px solid var(--line); border-radius: 18px; }
.zh p:first-child { margin-top: 0; }
.zh p:last-child { margin-bottom: 0; }

.steps { display: grid; gap: 12px; margin-top: 24px; counter-reset: guide-step; }
.step { position: relative; padding: 22px 24px 22px 72px; background: rgba(248, 250, 252, 0.78); border: 1px solid var(--line); border-radius: 18px; }
.step::before {
  position: absolute;
  top: 20px;
  left: 20px;
  display: grid;
  width: 34px;
  height: 34px;
  place-items: center;
  counter-increment: guide-step;
  content: counter(guide-step);
  color: #fff;
  background: var(--blue);
  border-radius: 50%;
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 780;
}
.step h3 { margin: 0 0 5px; font-size: 20px; }
.step p { margin: 0; font-size: 15px; }

.notice { padding: 22px 24px; border-left: 4px solid var(--amber); background: rgba(232, 166, 52, 0.1); border-radius: 6px 18px 18px 6px; }
.notice p { margin: 0; }
.limits { padding: 26px; background: rgba(9, 11, 16, 0.93); border-radius: 22px; color: #fff; }
.limits h3 { margin-top: 0; }
.limits p, .limits li { color: rgba(255, 255, 255, 0.7); }

.related { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; margin-top: 24px; }
.related a { padding: 20px; text-decoration: none; background: rgba(248, 250, 252, 0.76); border: 1px solid var(--line); border-radius: 18px; }
.related a:hover { border-color: rgba(45, 104, 215, 0.45); }
.related strong { display: block; margin-bottom: 5px; font-size: 19px; }
.related span { color: var(--muted); font-family: var(--sans); font-size: 13px; line-height: 1.45; }

.final-cta { display: grid; grid-template-columns: auto 1fr auto; gap: 22px; align-items: center; margin-top: 72px; padding: 28px; background: rgba(248, 250, 252, 0.8); border: 1px solid var(--line); border-radius: 26px; }
.final-cta img { width: 68px; height: 68px; }
.final-cta h2 { margin: 0; font-size: 31px; }
.final-cta p { margin: 5px 0 0; color: var(--muted); font-family: var(--sans); font-size: 14px; }
footer { display: flex; justify-content: space-between; gap: 18px; margin-top: 34px; color: var(--muted); font-family: var(--sans); font-size: 12px; }

@media (max-width: 760px) {
  .hero { padding: 72px 14px 52px; }
  .proof { grid-template-columns: 1fr; padding: 22px; }
  .nav-actions > a:not(.download) { display: none; }
  .related { grid-template-columns: 1fr; }
  .final-cta { grid-template-columns: auto 1fr; }
  .final-cta .button { grid-column: 1 / -1; justify-content: center; }
}

@media (max-width: 520px) {
  h1 { font-size: 52px; }
  .shell { width: min(100% - 20px, 1080px); }
  .final-cta { grid-template-columns: 1fr; text-align: center; }
  .final-cta img { margin: 0 auto; }
  footer { flex-direction: column; text-align: center; }
}

@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

@media (prefers-color-scheme: dark) {
  :root { --ink: #f4f5f7; --slate: #c9cdd5; --fog: #111318; --paper: #191c22; --muted: #a4aab5; --line: rgba(255, 255, 255, 0.1); }
  body { background-color: #111318; }
  .button-secondary, .zh, .step, .related a, .final-cta { background: rgba(25, 28, 34, 0.9); }
}