:root {
  --bg-color: #050816;
  --bg-elevated: rgba(8, 16, 32, 0.96);
  --bg-elevated-soft: rgba(10, 20, 40, 0.92);
  --accent: #06b6d4;
  --accent-soft: rgba(6, 182, 212, 0.16);
  --accent-alt: #f59e0b;
  --accent-alt-soft: rgba(245, 158, 11, 0.22);
  --text-main: #f9fafb;
  --text-muted: #9ca3af;
  --border-subtle: rgba(148, 163, 184, 0.3);
  --shadow-soft: 0 18px 45px rgba(15, 23, 42, 0.7);
  --shadow-header: 0 10px 30px rgba(15, 23, 42, 0.7);
  --radius-lg: 18px;
  --radius-md: 12px;
  --radius-pill: 999px;
  --container-max: 1040px;
  --transition-fast: 0.18s ease-out;
  --transition-med: 0.25s ease-out;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
}

body {
  min-height: 100vh;
  color: var(--text-main);
  font-family: "PingFang SC", "Hiragino Sans GB", "Source Han Sans SC", "Noto Sans CJK SC", "Microsoft YaHei", sans-serif;
  background:
    radial-gradient(circle at 0% 0%, rgba(6, 182, 212, 0.18), transparent 55%),
    radial-gradient(circle at 100% 100%, rgba(245, 158, 11, 0.15), transparent 55%),
    repeating-linear-gradient(
      135deg,
      rgba(15, 23, 42, 0.9) 0,
      rgba(15, 23, 42, 0.9) 2px,
      #020617 2px,
      #020617 5px
    );
  -webkit-font-smoothing: antialiased;
  text-rendering: geometricPrecision;
}

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

a {
  color: inherit;
  text-decoration: none;
}

a:hover {
  text-decoration: none;
}

main {
  padding-top: 88px;
}

.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 20px;
}

.section {
  padding: 80px 0;
}

.section-alt {
  background: radial-gradient(circle at 0 0, rgba(148, 163, 184, 0.06), transparent 60%),
    radial-gradient(circle at 100% 100%, rgba(148, 163, 184, 0.04), transparent 55%),
    linear-gradient(to bottom, rgba(15, 23, 42, 0.9), rgba(15, 23, 42, 0.96));
  border-top: 1px solid rgba(148, 163, 184, 0.2);
  border-bottom: 1px solid rgba(148, 163, 184, 0.16);
}

.section-header {
  max-width: 720px;
  margin: 0 auto 40px;
  text-align: center;
}

.section-header h2 {
  margin: 0 0 16px;
  font-size: 28px;
  letter-spacing: 0.02em;
}

.section-header p {
  margin: 0;
  color: var(--text-muted);
  line-height: 1.7;
  font-size: 15px;
}

/* Header */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: radial-gradient(circle at 0 0, rgba(6, 182, 212, 0.22), transparent 55%),
    radial-gradient(circle at 100% 0, rgba(245, 158, 11, 0.22), transparent 55%),
    rgba(3, 7, 18, 0.96);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(148, 163, 184, 0.3);
  transition: box-shadow var(--transition-med), border-color var(--transition-med), background var(--transition-med);
}

.site-header.is-scrolled {
  box-shadow: var(--shadow-header);
  border-bottom-color: rgba(148, 163, 184, 0.6);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 14px 20px;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 6px 10px;
  border-radius: var(--radius-pill);
  background: radial-gradient(circle at 0 0, rgba(6, 182, 212, 0.3), transparent 55%);
}

.brand-mark {
  width: 30px;
  height: 30px;
}

.brand-text {
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  font-size: 14px;
}

.nav {
  display: flex;
  align-items: center;
  gap: 18px;
  font-size: 14px;
}

.nav-link {
  position: relative;
  color: var(--text-muted);
  padding: 4px 0;
  transition: color var(--transition-fast);
}

.nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 0;
  height: 2px;
  border-radius: 999px;
  background: linear-gradient(to right, var(--accent), var(--accent-alt));
  transition: width var(--transition-fast);
}

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

.nav-link:hover::after {
  width: 100%;
}

.header-cta {
  white-space: nowrap;
}

.lang-switch {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 4px 10px;
  border-radius: var(--radius-pill);
  border: 1px solid rgba(148, 163, 184, 0.5);
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  background: rgba(15, 23, 42, 0.85);
  transition: background var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast), transform 0.12s ease-out;
}

.lang-switch:hover {
  color: var(--text-main);
  border-color: rgba(248, 250, 252, 0.85);
  background: rgba(15, 23, 42, 0.98);
  transform: translateY(-0.5px);
}

/* Buttons */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 9px 18px;
  border-radius: var(--radius-pill);
  border: 1px solid transparent;
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: transform 0.12s ease-out, box-shadow var(--transition-fast), border-color var(--transition-fast), background var(--transition-fast), color var(--transition-fast);
}

.btn-primary {
  background-image: linear-gradient(135deg, var(--accent), var(--accent-alt));
  color: #f9fafb;
  box-shadow: 0 12px 30px rgba(6, 182, 212, 0.65);
}

.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 18px 40px rgba(6, 182, 212, 0.85);
}

.btn-secondary {
  background: rgba(15, 23, 42, 0.85);
  color: var(--text-main);
  border-color: rgba(148, 163, 184, 0.5);
}

.btn-secondary:hover {
  border-color: rgba(248, 250, 252, 0.8);
  background: rgba(15, 23, 42, 0.98);
}

.btn-lg {
  padding: 11px 22px;
  font-size: 15px;
}

.btn-sm {
  padding: 6px 12px;
  font-size: 13px;
}

/* Hero */

.hero {
  padding-top: 72px;
}

.hero-inner {
  display: grid;
  grid-template-columns: minmax(0, 6fr) minmax(0, 5fr);
  gap: 40px;
  align-items: center;
}

.hero-copy {
  max-width: 560px;
}

.hero-title {
  margin: 0 0 16px;
  font-size: 32px;
  letter-spacing: 0.01em;
}

.hero-subtitle {
  margin: 0 0 18px;
  color: var(--text-muted);
  line-height: 1.7;
  font-size: 15px;
}

.hero-highlights {
  margin: 0 0 16px;
  padding-left: 18px;
  color: var(--text-muted);
  font-size: 14px;
  line-height: 1.7;
}

.hero-highlights li + li {
  margin-top: 4px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 12px;
}

.hero-note {
  margin: 0;
  font-size: 13px;
  color: var(--text-muted);
}

.hero-visual {
  display: flex;
  justify-content: center;
}

.hero-card {
  width: 100%;
  max-width: 420px;
  padding: 18px 18px 20px;
  border-radius: 24px;
  background: radial-gradient(circle at 0 0, rgba(6, 182, 212, 0.4), transparent 55%),
    radial-gradient(circle at 100% 100%, rgba(245, 158, 11, 0.35), transparent 55%),
    linear-gradient(145deg, rgba(15, 23, 42, 0.98), rgba(15, 23, 42, 0.92));
  border: 1px solid rgba(148, 163, 184, 0.45);
  box-shadow: var(--shadow-soft);
}

.hero-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
}

.hero-card-label {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.16em;
  color: var(--text-muted);
}

.hero-card-dot {
  width: 9px;
  height: 9px;
  border-radius: 999px;
  background: radial-gradient(circle at 30% 30%, #f9fafb, var(--accent));
  box-shadow: 0 0 18px rgba(6, 182, 212, 0.9);
}

.hero-flow {
  list-style: none;
  margin: 0;
  padding: 0;
}

.hero-flow li + li {
  margin-top: 12px;
}

.hero-flow h3 {
  margin: 0 0 4px;
  font-size: 15px;
}

.hero-flow p {
  margin: 0;
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.7;
}

/* Grids */

.how-grid,
.cap-grid,
.scn-grid,
.faq-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 22px;
}

.how-card,
.cap-card,
.scn-card,
.faq-item {
  padding: 18px 18px 20px;
  border-radius: var(--radius-lg);
  border: 1px solid rgba(148, 163, 184, 0.4);
  background: var(--bg-elevated);
  box-shadow: 0 14px 30px rgba(15, 23, 42, 0.6);
}

.how-card h3,
.cap-card h3,
.scn-card h3,
.faq-item h3 {
  margin: 0 0 6px;
  font-size: 15px;
}

.how-card p,
.cap-card p,
.scn-card p,
.faq-item p {
  margin: 0;
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.7;
}

/* Download section */

.download-layout {
  display: grid;
  grid-template-columns: minmax(0, 6.5fr) minmax(0, 4.5fr);
  gap: 32px;
  align-items: flex-start;
}

.download-main {
  padding: 20px 20px 22px;
  border-radius: var(--radius-lg);
  background: var(--bg-elevated);
  border: 1px solid rgba(148, 163, 184, 0.45);
  box-shadow: var(--shadow-soft);
}

.download-main h3 {
  margin-top: 0;
  margin-bottom: 6px;
  font-size: 16px;
}

.download-main p {
  margin-top: 0;
  margin-bottom: 12px;
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.7;
}

.download-main pre {
  margin: 8px 0 12px;
  padding: 10px 12px;
  border-radius: var(--radius-md);
  background: #020617;
  border: 1px solid rgba(30, 64, 175, 0.7);
  font-size: 12px;
  overflow-x: auto;
}

.download-main code,
.download-main pre code,
.security-box code,
.download-main .download-note code,
.checksum-box code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
}

.download-note {
  margin: 8px 0 16px;
  font-size: 12px;
  color: var(--text-muted);
}

.download-steps {
  margin-top: 18px;
}

.download-steps ol {
  margin: 8px 0 0;
  padding-left: 18px;
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.7;
}

.download-side {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.checksum-box,
.security-box {
  padding: 16px 16px 18px;
  border-radius: var(--radius-lg);
  background: var(--bg-elevated-soft);
  border: 1px solid rgba(148, 163, 184, 0.4);
}

.checksum-box h3,
.security-box h3 {
  margin-top: 0;
  margin-bottom: 6px;
  font-size: 15px;
}

.checksum-box p,
.security-box p,
.security-box ul {
  margin: 0;
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.7;
}

.security-box ul {
  padding-left: 18px;
}

.security-box li + li {
  margin-top: 4px;
}

/* Footer */

.site-footer {
  border-top: 1px solid rgba(148, 163, 184, 0.35);
  background: rgba(3, 7, 18, 0.96);
  backdrop-filter: blur(14px);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 16px 20px 18px;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.footer-mark {
  width: 26px;
  height: 26px;
}

.footer-title {
  margin: 0 0 2px;
  font-size: 15px;
}

.footer-subtitle {
  margin: 0;
  font-size: 12px;
  color: var(--text-muted);
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  font-size: 13px;
}

.footer-link {
  color: var(--text-muted);
  position: relative;
}

.footer-link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 0;
  height: 1px;
  background: linear-gradient(to right, var(--accent), var(--accent-alt));
  transition: width var(--transition-fast);
}

.footer-link:hover {
  color: var(--text-main);
}

.footer-link:hover::after {
  width: 100%;
}

.footer-meta {
  margin: 0;
  font-size: 12px;
  color: var(--text-muted);
}

/* Mobile download bar */

.mobile-download-bar {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 40;
  display: none;
  backdrop-filter: blur(16px);
}

.mobile-download-inner {
  margin: 0 auto 12px;
  max-width: var(--container-max);
  padding: 10px 16px;
  border-radius: var(--radius-pill);
  background: radial-gradient(circle at 0 0, rgba(6, 182, 212, 0.8), transparent 60%),
    radial-gradient(circle at 100% 100%, rgba(245, 158, 11, 0.9), transparent 60%),
    rgba(2, 6, 23, 0.98);
  border: 1px solid rgba(191, 219, 254, 0.7);
  box-shadow: 0 16px 40px rgba(15, 23, 42, 0.9);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.mobile-download-text {
  font-size: 13px;
}

/* Reveal animations */

.reveal {
  opacity: 0;
  transform: translateY(26px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.reveal.in-view {
  opacity: 1;
  transform: translateY(0);
}

/* Responsive adjustments */

@media (max-width: 960px) {
  .hero-inner {
    grid-template-columns: minmax(0, 1.1fr);
  }

  .hero-visual {
    display: none;
  }

  .download-layout {
    grid-template-columns: minmax(0, 1fr);
  }

  .how-grid,
  .cap-grid,
  .scn-grid,
  .faq-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 768px) {
  main {
    padding-top: 74px;
  }

  .section {
    padding: 60px 0;
  }

  .header-inner {
    padding-inline: 16px;
  }

  .nav {
    display: none;
  }

  .header-cta {
    display: none;
  }

  .hero {
    padding-top: 40px;
  }

  .section-header {
    text-align: left;
  }

  .section-header h2 {
    font-size: 22px;
  }

  .section-header p {
    font-size: 14px;
  }

  .how-grid,
  .cap-grid,
  .scn-grid,
  .faq-grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .footer-inner {
    flex-direction: column;
    align-items: flex-start;
  }

  .mobile-download-bar {
    display: block;
  }

  body {
    padding-bottom: 72px;
  }
}

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

  .reveal,
  .reveal.in-view {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .btn,
  .nav-link::after,
  .footer-link::after {
    transition: none;
  }
}