/* ============================================================
   Backpack Premium HTML — Core Styles
   品牌色：Backpack 官方红 #E33E3F
   字体：Plus Jakarta Sans (local woff2)
   ============================================================ */
* { box-sizing: border-box; }
*::before, *::after { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg-0);
  color: var(--text-primary);
  font-family: var(--font-body);
  font-size: var(--fs-16);
  line-height: var(--lh-base);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}

img, svg { display: block; max-width: 100%; height: auto; }
a { color: inherit; text-decoration: none; transition: color var(--d-fast) var(--ease-out); }
button { font: inherit; cursor: pointer; border: 0; background: none; color: inherit; }

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 700;
  letter-spacing: var(--letter-tight);
  line-height: var(--lh-tight);
  color: var(--text-primary);
  margin: 0;
}
h1 { font-size: clamp(40px, 6vw, 72px); font-weight: 800; }
h2 { font-size: clamp(28px, 3.6vw, 48px); }
h3 { font-size: var(--fs-22); }
h4 { font-size: var(--fs-18); }
p  { color: var(--text-secondary); margin: 0 0 var(--s-4); }

ul, ol { margin: 0; padding-left: 1.2em; color: var(--text-secondary); }
ul li, ol li { margin: 4px 0; }

::selection { background: var(--brand-500); color: #fff; }

.no-scroll { overflow: hidden; }

/* ============================================================
   Layout primitives
   ============================================================ */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--gutter);
}
.container--narrow { max-width: var(--container-narrow); }
.section { padding: clamp(64px, 9vw, 128px) 0; position: relative; }
.section--tight { padding: clamp(48px, 6vw, 80px) 0; }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 12px;
  border: 1px solid var(--border-soft);
  border-radius: var(--r-pill);
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: var(--letter-wide);
  text-transform: uppercase;
  color: var(--text-tertiary);
  background: var(--bg-glass);
  backdrop-filter: blur(8px);
}
.eyebrow .dot {
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--brand-500);
  box-shadow: 0 0 0 4px var(--brand-wash);
}

.section-title { max-width: 760px; margin: 0 auto var(--s-6); text-align: center; }
.section-title h2 { margin: var(--s-3) 0 var(--s-3); }
.section-title p { color: var(--text-tertiary); font-size: var(--fs-18); max-width: 640px; margin: 0 auto; }

/* ============================================================
   Header / Navigation
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  height: var(--header-h);
  display: flex;
  align-items: center;
  background: rgba(11, 11, 15, 0.7);
  backdrop-filter: saturate(140%) blur(20px);
  -webkit-backdrop-filter: saturate(140%) blur(20px);
  border-bottom: 1px solid var(--border-soft);
}
.site-header__inner {
  display: flex;
  align-items: center;
  gap: var(--s-5);
  width: 100%;
}
.site-logo { display: flex; align-items: center; gap: 10px; }
.site-logo img { width: 132px; height: auto; }

.nav {
  display: flex;
  align-items: center;
  gap: 4px;
  margin-left: var(--s-6);
}
.nav a {
  padding: 8px 12px;
  border-radius: var(--r-sm);
  font-size: var(--fs-14);
  color: var(--text-tertiary);
  font-weight: 500;
}
.nav a:hover { color: var(--text-primary); background: rgba(255, 255, 255, 0.04); }
.nav a.is-active { color: var(--text-primary); background: rgba(255, 255, 255, 0.06); }

.header-actions { margin-left: auto; display: flex; align-items: center; gap: 10px; }

.menu-toggle { display: none; }

.lang-switcher {
  display: flex; align-items: center; gap: 6px;
  padding: 6px 10px;
  border: 1px solid var(--border-soft);
  border-radius: var(--r-pill);
  font-size: var(--fs-12);
  color: var(--text-tertiary);
  cursor: pointer;
  background: rgba(255, 255, 255, 0.02);
}
.lang-switcher:hover { color: var(--text-primary); border-color: var(--border-strong); }
.lang-switcher select {
  background: transparent; border: 0; color: inherit;
  font: inherit; outline: none; cursor: pointer;
  appearance: none; -webkit-appearance: none;
  padding-right: 6px;
}
.lang-switcher select option { background: var(--bg-1); color: var(--text-primary); }

@media (max-width: 980px) {
  .nav { display: none; }
  .menu-toggle {
    display: inline-flex; align-items: center; justify-content: center;
    width: 40px; height: 40px;
    border-radius: var(--r-sm);
    border: 1px solid var(--border-soft);
    background: var(--surface-elevated);
  }
  .menu-toggle span, .menu-toggle span::before, .menu-toggle span::after {
    content: ""; display: block; width: 16px; height: 1.5px; background: var(--text-primary); position: relative;
  }
  .menu-toggle span::before { position: absolute; top: -5px; }
  .menu-toggle span::after  { position: absolute; top:  5px; }

  .nav.is-open {
    display: flex;
    position: absolute;
    top: var(--header-h);
    left: 0; right: 0;
    flex-direction: column;
    padding: var(--s-4);
    background: var(--bg-1);
    border-bottom: 1px solid var(--border-soft);
    z-index: 50;
  }
  .nav.is-open a { width: 100%; padding: 12px 14px; }
}

/* ============================================================
   Lang Switcher
   ============================================================ */
.lang-switcher {
  position: relative;
  margin-right: 8px;
}
.lang-switcher__btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  height: 36px;
  padding: 0 12px;
  border-radius: var(--r-pill);
  border: 1px solid var(--border-soft);
  background: var(--bg-glass);
  color: var(--text-secondary);
  font-family: var(--font-body);
  font-size: var(--fs-12);
  font-weight: 500;
  letter-spacing: 0.02em;
  cursor: pointer;
  transition: border-color var(--d-fast) var(--ease-out), color var(--d-fast) var(--ease-out);
}
.lang-switcher__btn:hover { border-color: var(--border-strong); color: var(--text-primary); }
.lang-switcher__globe { display: inline-flex; opacity: 0.85; }
.lang-switcher__caret { font-size: 10px; opacity: 0.7; transition: transform var(--d-fast) var(--ease-out); }
.lang-switcher.is-open .lang-switcher__caret { transform: rotate(180deg); }
.lang-switcher__menu {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  min-width: 240px;
  max-height: 360px;
  overflow-y: auto;
  background: var(--bg-2);
  border: 1px solid var(--border-soft);
  border-radius: var(--r-md);
  box-shadow: var(--shadow-lg);
  padding: 6px;
  display: none;
  z-index: 60;
  scrollbar-width: thin;
}
.lang-switcher.is-open .lang-switcher__menu { display: block; }
.lang-switcher__item {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  width: 100%;
  padding: 8px 10px;
  border-radius: var(--r-xs);
  text-align: left;
  color: var(--text-secondary);
  background: transparent;
  cursor: pointer;
  transition: background var(--d-fast) var(--ease-out), color var(--d-fast) var(--ease-out);
}
.lang-switcher__item:hover { background: var(--brand-wash); color: var(--text-primary); }
.lang-switcher__native { font-size: var(--fs-14); font-weight: 600; color: inherit; }
.lang-switcher__label { font-size: 11px; color: var(--text-muted); margin-left: 12px; }

@media (max-width: 720px) {
  .lang-switcher__btn { padding: 0 10px; height: 34px; }
  .lang-switcher__menu { min-width: 220px; right: -8px; }
}

/* ============================================================
   Buttons
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 18px;
  border-radius: var(--r-pill);
  font-size: var(--fs-14);
  font-weight: 600;
  letter-spacing: var(--letter-base);
  border: 1px solid transparent;
  transition: all var(--d-base) var(--ease-out);
  white-space: nowrap;
  text-decoration: none;
  font-family: var(--font-display);
}
.btn--primary {
  background: var(--brand-500);
  color: #fff;
  box-shadow: 0 6px 24px rgba(227, 62, 63, 0.30);
}
.btn--primary:hover {
  background: var(--brand-400);
  transform: translateY(-1px);
  box-shadow: 0 10px 32px rgba(227, 62, 63, 0.42);
}
.btn--ghost {
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-primary);
  border-color: var(--border-soft);
}
.btn--ghost:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: var(--border-strong);
}
.btn--outline {
  background: transparent;
  color: var(--text-primary);
  border-color: var(--border-soft);
}
.btn--outline:hover { border-color: var(--brand-500); color: var(--brand-500); }
.btn--lg { padding: 14px 26px; font-size: var(--fs-16); }
.btn--sm { padding: 6px 12px; font-size: var(--fs-12); }
.btn--block { width: 100%; }

.btn .arrow {
  display: inline-block;
  width: 14px; height: 14px;
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%23ffffff' stroke-width='2.4' stroke-linecap='round' stroke-linejoin='round'><path d='M5 12h14M13 5l7 7-7 7'/></svg>");
  background-size: contain;
  background-repeat: no-repeat;
  transition: transform var(--d-base) var(--ease-out);
}
.btn--ghost .arrow, .btn--outline .arrow {
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%23F4F4F6' stroke-width='2.4' stroke-linecap='round' stroke-linejoin='round'><path d='M5 12h14M13 5l7 7-7 7'/></svg>");
}
.btn:hover .arrow { transform: translateX(2px); }

/* ============================================================
   Hero
   ============================================================ */
.hero {
  position: relative;
  padding: clamp(96px, 12vw, 160px) 0 clamp(72px, 9vw, 128px);
  overflow: hidden;
  isolation: isolate;
}
.hero::before {
  content: ""; position: absolute; inset: 0;
  background: var(--grad-mesh);
  z-index: -2;
}
.hero::after {
  content: ""; position: absolute; inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.04) 1px, transparent 1px);
  background-size: 64px 64px;
  mask-image: radial-gradient(60% 50% at 50% 40%, #000 30%, transparent 80%);
  -webkit-mask-image: radial-gradient(60% 50% at 50% 40%, #000 30%, transparent 80%);
  z-index: -1;
}
.hero__inner {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: var(--s-7);
  align-items: center;
}
.hero__copy h1 { margin: var(--s-3) 0 var(--s-4); }
.hero__copy h1 .accent {
  background: var(--grad-brand);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent; color: transparent;
}
.hero__lede {
  font-size: var(--fs-18);
  color: var(--text-tertiary);
  max-width: 540px;
  margin-bottom: var(--s-6);
  line-height: 1.6;
}
.hero__cta {
  display: flex; gap: 12px; flex-wrap: wrap;
  margin-bottom: var(--s-6);
}
.hero__meta {
  display: flex; gap: 18px; align-items: center;
  color: var(--text-muted);
  font-size: var(--fs-12);
  font-family: var(--font-mono);
  letter-spacing: var(--letter-wide);
  text-transform: uppercase;
  flex-wrap: wrap;
}
.hero__meta strong { color: var(--text-primary); font-weight: 600; }
.hero__meta .sep { color: var(--text-faint); }

.hero__visual {
  position: relative;
  padding: 6px;
  border-radius: var(--r-xl);
  background: linear-gradient(140deg, rgba(227,62,63,0.30), rgba(74,158,255,0.10) 40%, rgba(11,11,15,0) 80%);
  border: 1px solid var(--border-soft);
  box-shadow: var(--shadow-lg);
}
.hero__visual img { border-radius: var(--r-lg); }

.hero__chips {
  position: absolute; display: flex; gap: 8px; flex-wrap: wrap;
  font-family: var(--font-mono); font-size: var(--fs-12);
}
.hero__chip {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 6px 10px;
  background: rgba(11, 11, 15, 0.85);
  border: 1px solid var(--border-soft);
  border-radius: var(--r-pill);
  color: var(--text-tertiary);
  backdrop-filter: blur(10px);
  font-weight: 500;
}
.hero__chip--brand { color: var(--brand-400); border-color: var(--border-accent); }
.hero__chip--blue  { color: var(--accent-blue); border-color: rgba(74,158,255,0.35); }
.hero__chip--green { color: var(--accent-green); border-color: rgba(52,199,89,0.35); }
.hero__chip .dot { width: 6px; height: 6px; border-radius: 50%; background: currentColor; }

@media (max-width: 980px) {
  .hero__inner { grid-template-columns: 1fr; }
  .hero__visual { order: -1; }
}

/* ============================================================
   Section: Quick Answer (AEO)
   ============================================================ */
.quick-answer {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: var(--s-6);
  align-items: start;
  background: linear-gradient(180deg, var(--surface-card) 0%, var(--bg-1) 100%);
  border: 1px solid var(--border-soft);
  border-radius: var(--r-xl);
  padding: clamp(24px, 4vw, 48px);
  position: relative;
  overflow: hidden;
}
.quick-answer::before {
  content: ""; position: absolute; left: 0; top: 0; bottom: 0;
  width: 4px;
  background: var(--grad-brand);
}
.quick-answer__answer h3 {
  font-size: clamp(22px, 2.4vw, 32px);
  margin-bottom: var(--s-4);
  line-height: 1.3;
}
.quick-answer__answer p { color: var(--text-secondary); font-size: var(--fs-18); }
.quick-answer__points { display: grid; gap: 12px; }
.quick-answer__point {
  display: grid; grid-template-columns: 40px 1fr; gap: 12px; align-items: start;
  padding: 16px;
  background: var(--surface-inset);
  border: 1px solid var(--border-soft);
  border-radius: var(--r-md);
  transition: all var(--d-base) var(--ease-out);
}
.quick-answer__point:hover { border-color: var(--border-accent); transform: translateX(4px); }
.quick-answer__point .badge {
  width: 40px; height: 40px;
  display: inline-flex; align-items: center; justify-content: center;
  background: var(--brand-wash);
  border: 1px solid var(--border-accent);
  border-radius: var(--r-sm);
  font-family: var(--font-mono); font-size: 13px; color: var(--brand-400);
  font-weight: 600;
}
.quick-answer__point h4 { font-size: var(--fs-16); margin-bottom: 4px; }
.quick-answer__point p { font-size: var(--fs-14); color: var(--text-tertiary); margin: 0; }

@media (max-width: 880px) { .quick-answer { grid-template-columns: 1fr; } }

/* ============================================================
   Trust Dashboard
   ============================================================ */
.trust {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}
.trust__card {
  position: relative;
  padding: 22px;
  border-radius: var(--r-lg);
  background: var(--surface-card);
  border: 1px solid var(--border-soft);
  overflow: hidden;
  transition: transform var(--d-base) var(--ease-out), border-color var(--d-base) var(--ease-out);
}
.trust__card:hover { transform: translateY(-3px); border-color: var(--border-accent); }
.trust__card .ring {
  position: absolute; right: -20px; top: -20px;
  width: 120px; height: 120px;
  border: 1px solid var(--border-accent);
  border-radius: 50%;
  opacity: 0.5;
}
.trust__card h4 { font-size: var(--fs-16); margin-bottom: 6px; }
.trust__card p  { color: var(--text-tertiary); font-size: var(--fs-14); margin: 0; }
.trust__icon {
  width: 38px; height: 38px;
  display: inline-flex; align-items: center; justify-content: center;
  background: var(--brand-wash);
  border: 1px solid var(--border-accent);
  border-radius: var(--r-sm);
  margin-bottom: 12px;
  font-family: var(--font-mono);
  color: var(--brand-400);
  font-size: 14px;
  font-weight: 700;
}

@media (max-width: 980px) { .trust { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 520px) { .trust { grid-template-columns: 1fr; } }

/* ============================================================
   Feature Grid
   ============================================================ */
.features {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 16px;
}
.feature {
  position: relative;
  grid-column: span 3;
  padding: 28px;
  background: var(--surface-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--r-lg);
  overflow: hidden;
  isolation: isolate;
  transition: all var(--d-base) var(--ease-out);
}
.feature::before {
  content: ""; position: absolute; inset: 0;
  background: radial-gradient(60% 40% at 0% 0%, rgba(227,62,63,0.10), transparent 60%);
  opacity: 0; transition: opacity var(--d-slow) var(--ease-out);
  z-index: -1;
}
.feature:hover { transform: translateY(-3px); border-color: var(--border-accent); }
.feature:hover::before { opacity: 1; }
.feature--wide { grid-column: span 6; }
.feature--narrow { grid-column: span 2; }
.feature__head { display: flex; gap: 14px; align-items: center; margin-bottom: var(--s-4); }
.feature__icon {
  width: 48px; height: 48px; display: inline-flex; align-items: center; justify-content: center;
  background: var(--surface-inset);
  border: 1px solid var(--border-soft);
  border-radius: var(--r-md);
}
.feature__title { font-size: var(--fs-22); }
.feature__copy { color: var(--text-tertiary); font-size: var(--fs-14); margin-bottom: var(--s-4); line-height: 1.6; }
.feature__media {
  margin-top: var(--s-4);
  border-radius: var(--r-md);
  border: 1px solid var(--border-soft);
  overflow: hidden;
  background: var(--bg-1);
}
.feature__media img { width: 100%; height: auto; }
.feature__meta {
  display: flex; gap: 8px; flex-wrap: wrap;
  font-family: var(--font-mono); font-size: var(--fs-12);
  color: var(--text-tertiary);
  margin-bottom: var(--s-3);
}
.feature__meta span { padding: 4px 8px; border: 1px solid var(--border-soft); border-radius: var(--r-pill); }

.feature__link {
  display: inline-flex; align-items: center; gap: 6px;
  color: var(--brand-400);
  font-size: var(--fs-14);
  font-weight: 600;
}
.feature__link:hover { color: var(--brand-500); }

@media (max-width: 980px) {
  .feature { grid-column: span 6; }
  .feature--narrow { grid-column: span 6; }
}

/* ============================================================
   Registration Journey
   ============================================================ */
.journey {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: var(--s-7);
  align-items: start;
}
.journey__copy h2 { margin-bottom: var(--s-3); }
.journey__copy p { color: var(--text-tertiary); font-size: var(--fs-18); }
.journey__steps { display: grid; gap: 12px; position: relative; }
.step {
  display: grid; grid-template-columns: 56px 1fr auto; gap: 16px; align-items: center;
  padding: 20px;
  background: var(--surface-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--r-md);
  position: relative;
  transition: all var(--d-base) var(--ease-out);
}
.step:hover { transform: translateX(4px); border-color: var(--border-accent); }
.step__index {
  width: 44px; height: 44px;
  display: inline-flex; align-items: center; justify-content: center;
  background: var(--surface-inset);
  border: 1px solid var(--border-accent);
  border-radius: var(--r-sm);
  font-family: var(--font-mono); color: var(--brand-400);
  font-weight: 700; font-size: 14px;
}
.step__title { font-size: var(--fs-16); }
.step__desc { color: var(--text-tertiary); font-size: var(--fs-14); margin: 4px 0 0; }
.step__cta { display: flex; align-items: center; gap: 8px; }

@media (max-width: 980px) { .journey { grid-template-columns: 1fr; } }

/* ============================================================
   Comparison Table
   ============================================================ */
.comparison {
  background: var(--surface-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--r-xl);
  overflow: hidden;
}
.comparison table { width: 100%; border-collapse: collapse; }
.comparison th, .comparison td {
  text-align: left;
  padding: 18px 22px;
  border-bottom: 1px solid var(--border-soft);
  font-size: var(--fs-14);
}
.comparison th { background: var(--surface-elevated); color: var(--text-tertiary); font-weight: 600; text-transform: uppercase; letter-spacing: var(--letter-wide); font-size: var(--fs-12); }
.comparison td { color: var(--text-secondary); }
.comparison tr:last-child td { border-bottom: 0; }
.comparison .col-self { color: var(--brand-400); font-weight: 600; }
.comparison .cell-strong { color: var(--text-primary); font-weight: 500; }
.comparison .cell-soft { color: var(--text-tertiary); }
.comparison-wrap { overflow-x: auto; }
@media (max-width: 720px) { .comparison th, .comparison td { padding: 14px 16px; } }

/* ============================================================
   Safety Center
   ============================================================ */
.safety {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: var(--s-6);
  align-items: start;
  background: linear-gradient(180deg, var(--surface-card) 0%, var(--bg-1) 100%);
  border: 1px solid var(--border-soft);
  border-radius: var(--r-xl);
  padding: clamp(24px, 4vw, 48px);
}
.safety__list { display: grid; gap: 12px; }
.safety__item {
  display: grid; grid-template-columns: 40px 1fr; gap: 12px; align-items: start;
  padding: 16px 18px;
  background: var(--surface-inset);
  border: 1px solid var(--border-soft);
  border-radius: var(--r-md);
  transition: all var(--d-base) var(--ease-out);
}
.safety__item:hover { border-color: var(--border-accent); }
.safety__item .icon {
  width: 40px; height: 40px;
  display: inline-flex; align-items: center; justify-content: center;
  background: var(--brand-wash);
  border: 1px solid var(--border-accent);
  border-radius: var(--r-sm);
  color: var(--brand-400);
  font-family: var(--font-mono);
  font-size: 13px; font-weight: 700;
}
.safety__item h4 { font-size: var(--fs-16); margin-bottom: 4px; }
.safety__item p { font-size: var(--fs-14); color: var(--text-tertiary); margin: 0; }
@media (max-width: 880px) { .safety { grid-template-columns: 1fr; } }

/* ============================================================
   FAQ
   ============================================================ */
.faq { display: grid; gap: 12px; max-width: 880px; margin: 0 auto; }
.faq__item {
  border: 1px solid var(--border-soft);
  border-radius: var(--r-md);
  background: var(--surface-card);
  overflow: hidden;
  transition: border-color var(--d-base) var(--ease-out);
}
.faq__item[open] { border-color: var(--border-accent); }
.faq__q {
  list-style: none;
  cursor: pointer;
  padding: 20px 22px;
  display: flex; gap: 14px; align-items: center; justify-content: space-between;
  font-size: var(--fs-16); color: var(--text-primary);
  font-weight: 600;
}
.faq__q::-webkit-details-marker { display: none; }
.faq__q .chevron {
  width: 22px; height: 22px;
  border: 1px solid var(--border-soft);
  border-radius: 50%;
  position: relative;
  flex: none;
  transition: all var(--d-base) var(--ease-out);
}
.faq__q .chevron::before {
  content: ""; position: absolute; left: 50%; top: 50%;
  width: 9px; height: 1.5px; background: var(--text-tertiary);
  transform: translate(-50%, -50%);
}
.faq__q .chevron::after {
  content: ""; position: absolute; left: 50%; top: 50%;
  width: 1.5px; height: 9px; background: var(--text-tertiary);
  transform: translate(-50%, -50%);
  transition: transform var(--d-base) var(--ease-out);
}
.faq__item[open] .chevron { border-color: var(--brand-500); }
.faq__item[open] .chevron::after { transform: translate(-50%, -50%) rotate(90deg); opacity: 0; }
.faq__a { padding: 0 22px 22px; color: var(--text-tertiary); }
.faq__a p { margin-bottom: 12px; color: var(--text-secondary); }

/* ============================================================
   Final Conversion Banner
   ============================================================ */
.final-cta {
  position: relative;
  padding: clamp(48px, 7vw, 80px);
  border-radius: var(--r-xl);
  background:
    radial-gradient(60% 80% at 0% 0%, rgba(227,62,63,0.28), transparent 60%),
    radial-gradient(50% 60% at 100% 100%, rgba(74,158,255,0.18), transparent 60%),
    linear-gradient(180deg, var(--bg-2) 0%, var(--bg-0) 100%);
  border: 1px solid var(--border-soft);
  overflow: hidden;
  isolation: isolate;
  text-align: center;
}
.final-cta::after {
  content: ""; position: absolute; inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.04) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(60% 80% at 50% 50%, #000 30%, transparent 80%);
  -webkit-mask-image: radial-gradient(60% 80% at 50% 50%, #000 30%, transparent 80%);
  opacity: 0.5;
  z-index: -1;
}
.final-cta h2 { margin-bottom: var(--s-3); }
.final-cta p  { color: var(--text-tertiary); max-width: 580px; margin: 0 auto var(--s-5); }
.final-cta .cta-row { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; margin-bottom: var(--s-4); }
.final-cta .meta { font-size: var(--fs-12); color: var(--text-muted); font-family: var(--font-mono); letter-spacing: var(--letter-wide); text-transform: uppercase; }

/* ============================================================
   Footer
   ============================================================ */
.site-footer {
  background: var(--bg-1);
  border-top: 1px solid var(--border-soft);
  padding: var(--s-7) 0 var(--s-5);
  color: var(--text-tertiary);
}
.footer__grid {
  display: grid;
  grid-template-columns: 1.4fr 0.8fr 0.8fr 0.8fr 0.8fr;
  gap: var(--s-6);
  margin-bottom: var(--s-6);
}
.footer__col h5 {
  font-size: var(--fs-12); letter-spacing: var(--letter-wide); text-transform: uppercase;
  color: var(--text-muted); margin: 0 0 var(--s-3); font-weight: 600;
}
.footer__col a { display: block; padding: 4px 0; color: var(--text-tertiary); font-size: var(--fs-14); }
.footer__col a:hover { color: var(--text-primary); }
.footer__brand p { color: var(--text-tertiary); font-size: var(--fs-14); margin-top: 8px; max-width: 280px; }
.footer__bottom {
  display: flex; gap: 16px; flex-wrap: wrap; justify-content: space-between; align-items: center;
  border-top: 1px solid var(--border-soft);
  padding-top: var(--s-4);
  font-size: var(--fs-12);
  color: var(--text-muted);
}
.footer__bottom .links { display: flex; gap: 14px; }
.footer__bottom .links a:hover { color: var(--text-primary); }
@media (max-width: 880px) { .footer__grid { grid-template-columns: 1fr 1fr; } }
@media (max-width: 520px) { .footer__grid { grid-template-columns: 1fr; } }

/* ============================================================
   Sub-page Hero
   ============================================================ */
.page-hero {
  padding: clamp(72px, 9vw, 128px) 0 clamp(40px, 5vw, 64px);
  position: relative;
  overflow: hidden;
}
.page-hero::before {
  content: ""; position: absolute; inset: 0;
  background: var(--grad-mesh);
  z-index: -1;
}
.breadcrumb {
  display: flex; gap: 8px; align-items: center; flex-wrap: wrap;
  font-family: var(--font-mono); font-size: var(--fs-12);
  color: var(--text-muted);
  margin-bottom: var(--s-4);
}
.breadcrumb a:hover { color: var(--text-primary); }
.breadcrumb .sep { color: var(--text-faint); }
.page-hero h1 { font-size: clamp(36px, 5.4vw, 64px); margin-bottom: var(--s-3); }
.page-hero p  { color: var(--text-tertiary); max-width: 720px; font-size: var(--fs-18); }

/* ============================================================
   Prose
   ============================================================ */
.prose {
  max-width: 760px; margin: 0 auto;
  font-size: var(--fs-16); line-height: var(--lh-loose);
  color: var(--text-secondary);
}
.prose h2 { font-size: var(--fs-28); margin: var(--s-6) 0 var(--s-3); color: var(--text-primary); }
.prose h3 { font-size: var(--fs-22); margin: var(--s-5) 0 var(--s-2); color: var(--text-primary); }
.prose p  { margin-bottom: var(--s-3); }
.prose ul, .prose ol { margin-bottom: var(--s-3); }
.prose blockquote {
  margin: var(--s-4) 0;
  padding: 14px 18px;
  border-left: 3px solid var(--brand-500);
  background: var(--surface-inset);
  border-radius: 0 var(--r-sm) var(--r-sm) 0;
  color: var(--text-secondary);
}
.prose code {
  font-family: var(--font-mono);
  font-size: 0.92em;
  background: var(--surface-inset);
  padding: 2px 6px;
  border-radius: 4px;
  color: var(--brand-400);
}

/* ============================================================
   Card generic
   ============================================================ */
.card {
  padding: 22px;
  background: var(--surface-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--r-lg);
  transition: all var(--d-base) var(--ease-out);
}
.card:hover { border-color: var(--border-accent); transform: translateY(-2px); }
.card h4 { margin-bottom: 8px; }
.card p  { color: var(--text-tertiary); font-size: var(--fs-14); margin: 0; }

/* ============================================================
   Grid helpers
   ============================================================ */
.grid { display: grid; gap: 16px; }
.grid--2 { grid-template-columns: repeat(2, 1fr); }
.grid--3 { grid-template-columns: repeat(3, 1fr); }
.grid--4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 880px) {
  .grid--2, .grid--3, .grid--4 { grid-template-columns: 1fr; }
}

/* ============================================================
   Mobile sticky CTA
   ============================================================ */
.mobile-cta {
  display: none;
  position: fixed;
  left: 16px; right: 16px; bottom: 16px;
  z-index: 60;
  background: var(--bg-1);
  border: 1px solid var(--border-soft);
  border-radius: var(--r-pill);
  box-shadow: var(--shadow-lg);
  padding: 6px;
}
.mobile-cta__inner { display: flex; gap: 6px; align-items: center; }
.mobile-cta .btn { flex: 1; }
@media (max-width: 720px) { .mobile-cta { display: block; } }

/* ============================================================
   Download Page Platform Buttons
   ============================================================ */
.platform-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}
@media (max-width: 720px) { .platform-grid { grid-template-columns: 1fr; } }

.platform-card {
  display: grid; grid-template-columns: 60px 1fr auto; gap: 18px; align-items: center;
  padding: 24px;
  background: var(--surface-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--r-lg);
  transition: all var(--d-base) var(--ease-out);
}
.platform-card:hover { transform: translateY(-2px); border-color: var(--border-accent); }
.platform-card__icon {
  width: 60px; height: 60px;
  display: inline-flex; align-items: center; justify-content: center;
  background: var(--surface-inset);
  border: 1px solid var(--border-soft);
  border-radius: var(--r-md);
}
.platform-card__title { font-size: var(--fs-18); }
.platform-card__sub { font-size: var(--fs-12); color: var(--text-muted); font-family: var(--font-mono); letter-spacing: var(--letter-wide); text-transform: uppercase; }