:root {
  --c-bg: #ffffff;
  --c-surface: #f5f7fb;
  --c-text: #1a2030;
  --c-muted: #5b6577;
  --c-border: #e6eaf0;
  --c-accent: #6d5efc;
  --c-accent-hover: #5847e0;
  --c-accent-soft: #eef0ff;
  --c-radius: 14px;
  --c-shadow: 0 10px 34px rgba(28, 26, 64, .09);
  --c-maxw: 1120px;
  --c-transition: .2s ease;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  color: var(--c-text);
  background: var(--c-bg);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

.container { max-width: var(--c-maxw); margin: 0 auto; padding: 0 20px; }

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

img { max-width: 100%; display: block; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, .86);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--c-border);
}
.site-header__inner { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 800; font-size: 18px; color: var(--c-text); }
.brand__logo { height: 32px; width: 32px; }
.brand:hover { color: var(--c-text); }

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: 0;
  cursor: pointer;
  padding: 8px;
}
.nav-toggle span { width: 24px; height: 2px; background: var(--c-text); border-radius: 2px; }

.primary-nav { display: flex; align-items: center; gap: 22px; }
.primary-nav a { color: var(--c-muted); font-size: 15px; font-weight: 500; }
.primary-nav a:hover, .primary-nav a.active { color: var(--c-accent); }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 18px;
  border-radius: 10px;
  font-weight: 600;
  font-size: 15px;
  cursor: pointer;
  border: 1px solid transparent;
  transition: background var(--c-transition), border-color var(--c-transition), color var(--c-transition);
}
.btn--accent { background: var(--c-accent); color: #fff; }
.btn--accent:hover { background: var(--c-accent-hover); color: #fff; }
.btn--ghost { background: #fff; color: var(--c-text); border-color: var(--c-border); }
.btn--ghost:hover { border-color: var(--c-accent); color: var(--c-accent); }
.btn--lg { padding: 13px 26px; font-size: 16px; }

.hero { padding: 78px 0 60px; background: linear-gradient(180deg, var(--c-accent-soft), #fff 72%); }
.hero__grid { display: grid; grid-template-columns: 1.1fr .9fr; gap: 44px; align-items: center; }
.hero h1 { font-size: 44px; line-height: 1.18; margin: 0 0 16px; font-weight: 800; letter-spacing: -.5px; }
.hero p { font-size: 17px; color: var(--c-muted); margin: 0 0 28px; }
.hero__cta { display: flex; gap: 14px; flex-wrap: wrap; }
.hero__visual { width: 100%; }

.section { padding: 64px 0; }
.section--alt { background: var(--c-surface); }
.section-title { font-size: 30px; font-weight: 800; margin: 0 0 10px; text-align: center; letter-spacing: -.3px; }
.section-sub { text-align: center; color: var(--c-muted); margin: 0 0 42px; font-size: 16px; }

.prose { max-width: 820px; margin: 0 auto; }
.prose p { margin: 0 0 14px; }
.prose h2 { font-size: 24px; margin: 30px 0 12px; }
.prose blockquote {
  border-left: 4px solid var(--c-accent);
  background: #fff;
  margin: 0 0 16px;
  padding: 12px 18px;
  border-radius: 0 10px 10px 0;
  color: var(--c-muted);
}

.feature-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.feature-card {
  background: #fff;
  border: 1px solid var(--c-border);
  border-radius: var(--c-radius);
  padding: 26px;
  transition: box-shadow var(--c-transition), transform var(--c-transition);
}
.feature-card:hover { box-shadow: var(--c-shadow); transform: translateY(-3px); }
.feature-card__ic {
  width: 46px;
  height: 46px;
  border-radius: 12px;
  background: var(--c-accent-soft);
  color: var(--c-accent);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 14px;
}
.feature-card h3 { margin: 0 0 8px; font-size: 18px; }
.feature-card p { margin: 0; color: var(--c-muted); font-size: 14.5px; }

.protocol-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }
.protocol-item { background: #fff; border: 1px solid var(--c-border); border-radius: var(--c-radius); padding: 18px 20px; transition: box-shadow var(--c-transition), transform var(--c-transition); }
.protocol-item:hover { box-shadow: var(--c-shadow); transform: translateY(-3px); }
.protocol-item__name { display: block; font-weight: 700; font-size: 16px; color: var(--c-text); margin-bottom: 4px; }
.protocol-item__desc { display: block; font-size: 13.5px; color: var(--c-muted); }

.steps { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; max-width: 880px; margin: 0 auto; }
.step { display: flex; gap: 14px; background: #fff; border: 1px solid var(--c-border); border-radius: var(--c-radius); padding: 18px; }
.step__num {
  flex: 0 0 32px;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--c-accent);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
}
.step h4 { margin: 0 0 4px; font-size: 16px; }
.step p { margin: 0; color: var(--c-muted); font-size: 14px; }

.download-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.platform-card { border: 1px solid var(--c-border); border-radius: var(--c-radius); padding: 26px; text-align: center; background: #fff; }
.platform-card h3 { margin: 0 0 4px; font-size: 19px; }
.platform-card .ver { color: var(--c-muted); font-size: 13.5px; margin: 0 0 18px; }
.platform-card ul { list-style: none; margin: 0 0 18px; padding: 0; display: flex; flex-direction: column; gap: 9px; }
.platform-card a.dl-link { color: var(--c-accent); font-size: 14.5px; font-weight: 600; }
.platform-card a.dl-link:hover { color: var(--c-accent-hover); }

.links-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.link-card { border: 1px solid var(--c-border); border-radius: var(--c-radius); padding: 22px; background: #fff; }
.link-card h4 { margin: 0 0 6px; font-size: 16px; }
.link-card a { font-weight: 600; }
.link-card p { margin: 0; color: var(--c-muted); font-size: 14px; }

.note { max-width: 820px; margin: 22px auto 0; text-align: center; color: var(--c-muted); font-size: 14px; }

.faq-item { background: #fff; border: 1px solid var(--c-border); border-radius: var(--c-radius); padding: 18px 20px; margin-bottom: 14px; }
.faq-item h3 { margin: 0 0 8px; font-size: 16px; color: var(--c-accent); }
.faq-item p { margin: 0; color: var(--c-muted); font-size: 14.5px; }
.faq-group { font-size: 20px; font-weight: 800; margin: 30px 0 14px; }

.footer { background: #14121f; color: #c4cbd6; padding: 56px 0 26px; margin-top: 40px; }
.footer__inner { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 36px 40px; }
.footer__brand { max-width: 320px; }
.footer__logo { height: 32px; margin-bottom: 14px; }
.footer__brand p { margin: 0; font-size: 14px; line-height: 1.7; }
.footer__col h4 { color: #fff; font-size: 14px; margin: 0 0 14px; font-weight: 700; }
.footer__links { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 10px; }
.footer__links a { color: #c4cbd6; font-size: 14px; }
.footer__links a:hover { color: #fff; }
.footer__copy { text-align: center; border-top: 1px solid rgba(255, 255, 255, .08); margin: 30px 0 0; padding-top: 20px; font-size: 13px; color: #8b93a3; }

@media (max-width: 900px) {
  .hero__grid { grid-template-columns: 1fr; }
  .hero__visual { max-width: 420px; margin: 0 auto; }
  .feature-grid, .download-grid, .links-grid, .protocol-grid, .stats { grid-template-columns: 1fr 1fr; }
  .steps { grid-template-columns: 1fr; }
}

@media (max-width: 760px) {
  .primary-nav {
    display: none;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: flex-start;
    gap: 14px;
    background: #fff;
    border-bottom: 1px solid var(--c-border);
    padding: 16px 20px;
  }
  .primary-nav.open { display: flex; }
  .nav-toggle { display: flex; }
  .footer__inner { grid-template-columns: 1fr 1fr; }
  .hero h1 { font-size: 34px; }
}

@media (max-width: 520px) {
  .feature-grid, .download-grid, .links-grid, .protocol-grid, .stats { grid-template-columns: 1fr; }
  .footer__inner { grid-template-columns: 1fr; }
  .hero h1 { font-size: 30px; }
}

.link-more {
  display: inline-block;
  margin-top: 12px;
  color: var(--c-accent);
  font-weight: 700;
  font-size: 14px;
  text-decoration: none;
  transition: var(--c-transition);
}
.link-more:hover {
  color: var(--c-accent-hover);
  transform: translateX(3px);
}
.feature-card h3 a, a.link-more { color: var(--c-accent); }

.friend-links { display: flex; flex-wrap: wrap; gap: 14px 26px; justify-content: center; }
.friend-links a { color: var(--c-accent); font-size: 15px; font-weight: 500; }
.friend-links a:hover { color: var(--c-accent-hover); }

.hero__badge { display: inline-block; padding: 6px 14px; border: 1px solid var(--c-accent); color: var(--c-accent); border-radius: 999px; font-size: 13px; font-weight: 600; margin: 0 0 18px; }

.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; }
.stat { text-align: center; padding: 26px 16px; background: var(--c-surface); border: 1px solid var(--c-border); border-radius: var(--c-radius); }
.stat__num { display: block; font-size: 34px; font-weight: 800; color: var(--c-accent); line-height: 1.1; }
.stat__label { display: block; margin-top: 8px; font-size: 14px; color: var(--c-muted); }

.primary-nav a { position: relative; }
.primary-nav a.active::after { content: ""; position: absolute; left: 0; right: 0; bottom: -6px; height: 2px; border-radius: 2px; background: var(--c-accent); }

.platform-card, .link-card { transition: box-shadow var(--c-transition), transform var(--c-transition); }
.platform-card:hover, .link-card:hover { box-shadow: var(--c-shadow); transform: translateY(-3px); }

.to-top { position: fixed; right: 22px; bottom: 22px; z-index: 60; width: 46px; height: 46px; border: 0; border-radius: 50%; background: var(--c-accent); color: #fff; display: flex; align-items: center; justify-content: center; cursor: pointer; box-shadow: var(--c-shadow); opacity: 0; transform: translateY(12px) scale(.9); pointer-events: none; transition: opacity .25s ease, transform .25s ease, background .2s ease; }
.to-top.show { opacity: 1; transform: none; pointer-events: auto; }
.to-top:hover { background: var(--c-accent-hover); }

html.anim .hero, html.anim .section, html.anim .footer { opacity: 0; transform: translateY(20px); transition: opacity .6s ease, transform .6s ease; }
html.anim .hero.in-view, html.anim .section.in-view, html.anim .footer.in-view { opacity: 1; transform: none; }

.download-cta { text-align: center; margin: 8px 0 16px; }
.dl-btn { width: 100%; max-width: 340px; justify-content: center; font-size: 17px; padding: 15px 26px; }
.dl-btn svg { width: 20px; height: 20px; }
.download-meta { text-align: center; color: var(--c-muted); font-size: 14px; margin: 0 0 18px; }
.download-links { display: flex; flex-wrap: wrap; gap: 10px 22px; justify-content: center; margin-bottom: 20px; }
.download-links a { color: var(--c-accent); font-weight: 600; font-size: 14.5px; }
.download-links a:hover { color: var(--c-accent-hover); }

.popup-overlay { display: none; position: fixed; inset: 0; background: rgba(20,18,31,.45); backdrop-filter: blur(4px); z-index: 9999; justify-content: center; align-items: center; }
.popup-overlay.active { display: flex; }
.popup { background: #fff; border-radius: var(--c-radius); padding: 38px 32px 30px; max-width: 400px; width: 90%; text-align: center; box-shadow: var(--c-shadow); animation: popupIn .25s ease; }
@keyframes popupIn { from { opacity: 0; transform: translateY(16px) scale(.96); } to { opacity: 1; transform: none; } }
.popup-ic { display: flex; align-items: center; justify-content: center; width: 56px; height: 56px; margin: 0 auto 16px; border-radius: 50%; background: var(--c-accent-soft); color: var(--c-accent); }
.popup-ic svg { width: 26px; height: 26px; }
.popup h3 { font-size: 1.25rem; font-weight: 800; margin: 0 0 10px; color: var(--c-text); }
.popup p { font-size: .92rem; color: var(--c-muted); margin: 0 0 26px; line-height: 1.6; }
.popup-btns { display: flex; gap: 12px; justify-content: center; }
.popup-btns .btn { min-width: 110px; }