:root {
  --ink: #142033;
  --blue: #1a4b7c;
  --muted: #5c6b78;
  --paper: #eef1f4;
  --white: #ffffff;
  --line: #d5dde5;
  --serif: "Songti SC", "STSong", "SimSun", serif;
  --sans: "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif;
  --wrap: 1120px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.7;
}

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

a { color: var(--blue); text-underline-offset: 0.18em; }

a:hover { color: #0e3358; }

:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: 3px;
}

.skip {
  position: absolute;
  left: 1rem;
  top: -4rem;
  background: var(--ink);
  color: var(--white);
  padding: 0.4rem 0.8rem;
  z-index: 10;
}

.skip:focus { top: 0.5rem; }

.wrap {
  width: min(var(--wrap), calc(100% - 2.5rem));
  margin-inline: auto;
}

.site-header {
  background: var(--white);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 5;
}

.header-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 72px;
  gap: 1rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  color: var(--ink);
  text-decoration: none;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.brand-mark {
  width: 2rem;
  height: 2rem;
  display: grid;
  place-items: center;
  background: var(--ink);
  color: var(--white);
  font-family: var(--serif);
  font-size: 1.05rem;
}

.nav-toggle {
  display: none;
  border: 1px solid var(--line);
  background: var(--white);
  color: var(--ink);
  font: inherit;
  padding: 0.35rem 0.75rem;
  cursor: pointer;
}

.site-nav ul {
  display: flex;
  align-items: center;
  gap: 0.25rem 1.4rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.site-nav a {
  color: var(--ink);
  text-decoration: none;
  padding: 0.35rem 0;
}

.site-nav a[aria-current="page"],
.page-product .has-sub > a {
  box-shadow: inset 0 -2px 0 var(--blue);
}

.has-sub { position: relative; }

.has-sub ul {
  display: none;
  position: absolute;
  top: 100%;
  left: -0.8rem;
  min-width: 11rem;
  flex-direction: column;
  align-items: stretch;
  gap: 0;
  background: var(--white);
  border: 1px solid var(--line);
  padding: 0.4rem 0;
}

.has-sub li a {
  display: block;
  padding: 0.4rem 1rem;
}

.has-sub li a:hover,
.has-sub li a:focus-visible { background: var(--paper); }

.has-sub:hover > ul,
.has-sub:focus-within > ul { display: flex; }

.hero { padding: 3.5rem 0 2.5rem; }

.hero-grid,
.product-grid,
.about-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
  gap: 3rem;
  align-items: center;
}

.hero-grid > *,
.product-grid > *,
.about-grid > *,
.footer-grid > * {
  min-width: 0;
}

.kicker {
  margin: 0 0 0.6rem;
  color: var(--blue);
  letter-spacing: 0.14em;
  font-size: 0.82rem;
}

h1, h2, h3 { font-family: var(--serif); font-weight: 600; line-height: 1.3; }

h1 { font-size: clamp(2rem, 4vw, 3.15rem); margin: 0 0 1rem; }

h2 { font-size: 1.7rem; margin: 0 0 1rem; }

.lede, .hero p { color: var(--muted); max-width: 38rem; }

.hero p { margin: 0 0 1.2rem; }

.frame {
  margin: 0;
  background: var(--white);
  border: 1px solid var(--line);
  padding: 0.6rem;
}

.frame img { width: 100%; height: auto; }

.catalog { padding: 1rem 0 3.5rem; }

.catalog-list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--ink);
}

.catalog-list a {
  display: grid;
  grid-template-columns: 4.5rem 1fr auto;
  gap: 1rem;
  align-items: baseline;
  padding: 1.15rem 0.2rem;
  border-bottom: 1px solid var(--line);
  color: var(--ink);
  text-decoration: none;
}

.catalog-list a:hover { color: var(--blue); }

.catalog-list span {
  font-family: var(--serif);
  color: var(--blue);
  font-size: 1.15rem;
}

.catalog-list strong { font-size: 1.15rem; font-weight: 600; }

.catalog-list em {
  color: var(--muted);
  font-style: normal;
  font-size: 0.95rem;
}

.about-strip {
  background: var(--white);
  border-top: 1px solid var(--line);
  padding: 3rem 0;
}

.about-strip p { max-width: 40rem; color: var(--muted); }

.page-head { padding: 2.8rem 0 0.5rem; }

.crumb { margin: 0 0 1rem; color: var(--muted); font-size: 0.92rem; }

.crumb a { color: var(--muted); }

.product,
.contact-block { padding: 1.5rem 0 3.5rem; }

.specs { margin: 0; }

.specs div {
  display: grid;
  grid-template-columns: 6.5rem 1fr;
  gap: 1rem;
  padding: 0.85rem 0;
  border-top: 1px solid var(--line);
}

.specs dt { color: var(--muted); }

.specs dd { margin: 0; }

.note {
  color: var(--muted);
  margin: 1.2rem 0 0;
}

.related {
  padding-bottom: 3rem;
}

.related ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem 1.4rem;
}

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

.plain-list li {
  padding: 0.7rem 0;
  border-top: 1px solid var(--line);
}

.site-footer {
  background: var(--ink);
  color: #d5dde6;
  padding: 2.4rem 0 2rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(0, 1fr) minmax(0, 1.2fr);
  gap: 2rem;
}

.site-footer a { color: #ffffff; }

.site-footer h2 {
  font-family: var(--sans);
  font-size: 0.82rem;
  letter-spacing: 0.12em;
  margin: 0 0 0.7rem;
  color: #9aabba;
}

.site-footer ul { list-style: none; margin: 0; padding: 0; }

.site-footer li { margin: 0.25rem 0; }

.site-footer p { margin: 0.2rem 0; }

.copyright {
  margin-top: 1.8rem;
  padding-top: 1rem;
  border-top: 1px solid rgba(255, 255, 255, 0.12);
  color: #9aabba;
  font-size: 0.88rem;
}

@media (max-width: 860px) {
  .nav-toggle { display: block; }

  .site-nav {
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    top: 72px;
    background: var(--white);
    border-bottom: 1px solid var(--line);
    padding: 0.4rem 1.25rem 1rem;
  }

  .site-nav.is-open { display: block; }

  .site-nav ul,
  .has-sub ul {
    display: flex;
    flex-direction: column;
    align-items: stretch;
    position: static;
    border: 0;
    padding: 0;
    min-width: 0;
    background: transparent;
  }

  .has-sub ul { padding-left: 0.8rem; }

  .site-nav a { display: block; padding: 0.55rem 0; }

  .hero-grid,
  .product-grid,
  .about-grid,
  .footer-grid { grid-template-columns: 1fr; gap: 1.5rem; }

  .catalog-list a { grid-template-columns: 3rem 1fr; }

  .catalog-list em { grid-column: 2; }
}

@media (max-width: 560px) {
  .wrap { width: min(var(--wrap), calc(100% - 1.5rem)); }

  .specs div { grid-template-columns: 1fr; gap: 0.15rem; }
}