:root {
  color-scheme: light dark;
  --canvas: #f5f7fa;
  --surface: #ffffff;
  --ink: #111b2c;
  --muted: #5f6d7e;
  --line: #d9e0e8;
  --accent: #315b8c;
  --accent-deep: #23456e;
  --accent-soft: #e8eef6;
  --dark: #101b2d;
  --on-dark: #f6f8fb;
  --on-dark-muted: #bdc9d7;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  font-synthesis: none;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: var(--canvas); color: var(--ink); overflow-wrap: anywhere; }
.skip-link { position: fixed; top: 8px; left: 8px; z-index: 10; min-height: 44px; display: inline-flex; align-items: center; padding: 8px 13px; background: var(--dark); color: var(--on-dark); transform: translateY(-160%); }
.skip-link:focus { transform: translateY(0); }
a { color: inherit; text-underline-offset: .24em; }
img { display: block; max-width: 100%; }
::selection { background: var(--accent); color: #fff; }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 4px; }
.site-header, .page-shell, .site-footer { width: min(1120px, calc(100% - 44px)); margin-inline: auto; }

.site-header { min-height: 76px; display: flex; align-items: center; justify-content: space-between; gap: 24px; border-bottom: 1px solid var(--line); }
.brand { display: inline-flex; align-items: center; gap: 11px; color: var(--ink); font-weight: 820; text-decoration: none; }
.brand img { width: 40px; height: 40px; border-radius: 12px; }
.nav { display: flex; align-items: center; gap: 22px; }
.nav a { min-height: 44px; display: inline-flex; align-items: center; color: var(--muted); font-size: .9rem; text-decoration: none; }
.nav a:hover { color: var(--accent); }
.page-shell { padding-bottom: 92px; }

.hero { min-height: 590px; display: grid; grid-template-columns: minmax(0, 1.12fr) minmax(300px, .88fr); align-items: center; gap: clamp(48px, 8vw, 112px); padding-block: clamp(70px, 10vw, 122px); }
h1, h2, h3, p { margin-top: 0; }
h1 { max-width: 15ch; margin-bottom: 25px; font-size: clamp(3rem, 5.3vw, 4.6rem); font-weight: 680; letter-spacing: -.04em; line-height: 1.02; text-wrap: balance; }
h1 span { display: block; white-space: nowrap; }
.lead { max-width: 38rem; margin-bottom: 0; color: var(--muted); font-size: clamp(1.03rem, 1.6vw, 1.2rem); line-height: 1.75; }
.actions { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-top: 28px; }
.button { min-height: 48px; display: inline-flex; align-items: center; justify-content: center; padding: 10px 18px; border-radius: 10px; font-weight: 760; text-decoration: none; }
.button-primary { background: var(--accent); color: #fff; transition: background 160ms ease, transform 160ms ease; }
.button-primary:hover { background: var(--accent-deep); transform: translateY(-2px); }
.button-secondary, .button-disabled { border: 1px solid var(--line); color: var(--muted); }
.button-disabled { cursor: default; }
.text-link { min-height: 48px; display: inline-flex; align-items: center; padding-inline: 8px; color: var(--accent-deep); font-weight: 720; }
.version-note { margin-top: 15px; color: var(--muted); font-family: ui-monospace, Consolas, monospace; font-size: .78rem; }
.product-identity { padding: clamp(28px, 5vw, 52px); border-radius: 28px; background: var(--dark); color: var(--on-dark); }
.product-identity img { width: 148px; height: 148px; border-radius: 34px; box-shadow: 0 22px 50px rgba(0,0,0,.28); }
.formula-note { margin-top: 40px; padding-top: 24px; border-top: 1px solid rgba(255,255,255,.15); }
.formula-note span, .formula-note strong, .formula-note b { display: block; }
.formula-note span { color: var(--on-dark-muted); font-size: .75rem; letter-spacing: .08em; }
.formula-note strong { margin-top: 8px; font-size: .95rem; font-weight: 560; }
.formula-note b { margin-top: 12px; color: #a9c9ee; font-size: 1.6rem; font-variant-numeric: tabular-nums; }

.section { display: grid; grid-template-columns: minmax(240px, .76fr) minmax(0, 1.24fr); gap: clamp(42px, 8vw, 112px); padding-block: clamp(62px, 9vw, 104px); border-top: 1px solid var(--line); }
.section h2 { max-width: 11ch; margin-bottom: 15px; font-size: clamp(2.15rem, 4.8vw, 4.3rem); font-weight: 660; letter-spacing: -.04em; line-height: 1.03; text-wrap: balance; }
.section-intro { max-width: 28rem; color: var(--muted); line-height: 1.75; }
.feature-list { margin: 0; padding: 0; list-style: none; }
.feature-list li { padding-bottom: 26px; margin-bottom: 26px; border-bottom: 1px solid var(--line); }
.feature-list li:last-child { margin: 0; padding: 0; border: 0; }
.feature-list h3 { margin-bottom: 8px; font-size: 1.16rem; }
.feature-list p { max-width: 64ch; margin: 0; color: var(--muted); line-height: 1.75; }
.feature-list a { color: var(--accent-deep); }

.download-panel { padding: clamp(28px, 5vw, 54px); border-radius: 24px; background: var(--dark); color: var(--on-dark); }
.download-panel h3, .reading .download-panel h2 { margin-bottom: 12px; color: var(--on-dark); font-size: clamp(1.7rem, 3vw, 2.45rem); }
.download-panel p, .reading .download-panel p { max-width: 62ch; color: var(--on-dark-muted); line-height: 1.75; }
.download-panel .button-primary { margin-top: 8px; }
.download-meta { margin-top: 20px; color: var(--on-dark-muted); font-size: .82rem; line-height: 1.8; font-variant-numeric: tabular-nums; }
.download-meta code { font-family: ui-monospace, Consolas, monospace; }
.download-links { margin-top: 18px; display: flex; flex-wrap: wrap; gap: 18px; }
.download-links a { color: var(--on-dark); }
.notice { margin-top: 22px; padding-top: 22px; border-top: 1px solid rgba(255,255,255,.18); color: var(--on-dark-muted); }

.reading { max-width: 800px; padding-top: 54px; }
.reading h1 { max-width: none; margin-bottom: 16px; font-size: clamp(2.5rem, 6vw, 4.6rem); }
.reading .summary { color: var(--muted); font-size: 1.06rem; line-height: 1.82; }
.reading section { padding-top: 34px; }
.reading h2 { margin-bottom: 9px; color: var(--accent-deep); font-size: 1.28rem; }
.reading p, .reading li { color: var(--muted); line-height: 1.85; }
.reading footer { margin-top: 48px; padding-top: 24px; border-top: 1px solid var(--line); }

.site-footer { min-height: 120px; display: flex; justify-content: space-between; gap: 26px; padding-block: 30px; border-top: 1px solid var(--line); color: var(--muted); font-size: .9rem; }
.site-footer nav { display: flex; flex-wrap: wrap; align-content: flex-start; justify-content: flex-end; gap: 8px 18px; }
.site-footer a { min-height: 44px; display: inline-flex; align-items: center; }

@media (max-width: 760px) {
  .site-header, .page-shell, .site-footer { width: min(100% - 28px, 680px); }
  .site-header { align-items: flex-start; padding-block: 16px; }
  .nav { gap: 14px; }
  .nav a:nth-child(2) { display: none; }
  .hero { min-height: auto; grid-template-columns: 1fr; gap: 38px; padding-block: 54px 68px; }
  h1 { font-size: clamp(2.4rem, 10.2vw, 3.8rem); }
  .product-identity { display: grid; grid-template-columns: 96px 1fr; align-items: center; gap: 22px; }
  .product-identity img { width: 96px; height: 96px; border-radius: 24px; }
  .formula-note { margin: 0; padding: 0; border: 0; }
  .section { grid-template-columns: 1fr; }
  .section h2 { max-width: 14ch; }
  .site-footer { flex-direction: column; }
  .site-footer nav { justify-content: flex-start; }
}

@media (max-width: 500px) {
  .brand span { display: none; }
  .actions { align-items: stretch; flex-direction: column; }
  .button, .text-link { width: 100%; }
  .product-identity { grid-template-columns: 76px 1fr; padding: 24px; }
  .product-identity img { width: 76px; height: 76px; border-radius: 19px; }
}

@media (prefers-color-scheme: dark) {
  :root {
    --canvas: #0b121d;
    --surface: #101a28;
    --ink: #f1f5fa;
    --muted: #a5b2c3;
    --line: #273549;
    --accent: #76a4d7;
    --accent-deep: #8db5e1;
    --accent-soft: #1a2d43;
    --dark: #07101b;
  }
  .button-primary { color: #07101b; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .button-primary { transition: none; }
  .button-primary:hover { transform: none; }
}

@media print {
  .site-header, .site-footer, .actions { display: none; }
  .page-shell { width: 100%; padding: 0; }
}