/* ============================================================
   AI新知 · 科技媒体站 — 现代杂志风设计系统
   ============================================================ */
:root {
  --paper: #ffffff;
  --ink: #141414;
  --ink-soft: #2a2b2e;
  --surface: #f6f6f3;
  --surface-2: #efefeb;
  --line: #14141422;
  --line-strong: #141414;
  --muted: #666a63;
  --faint: #9a9d96;
  --violet: #5e4bd8;
  --violet-deep: #4a3bbd;
  --lime: #b8df45;
  --lime-ink: #4c6413;
  --coral: #e0603f;
  --dark: #131417;
  --dark-2: #1c1e23;
  --dark-line: #ffffff26;
  --dark-muted: #a3a69e;
  --display: "Noto Serif SC", "Songti SC", "STSong", "SimSun", Georgia, serif;
  --sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  --mono: "SF Mono", "SFMono-Regular", "Cascadia Code", Menlo, Consolas, monospace;
  --maxw: 1240px;
  --pad: clamp(20px, 4vw, 56px);
  --sec: clamp(56px, 7vw, 96px);
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  overflow-x: clip;
}
::selection { background: #5e4bd833; }
a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; height: auto; }
.skip-link {
  position: absolute; top: 0; left: 0; z-index: 200;
  width: 1px; height: 1px; margin: -1px; padding: 0; border: 0;
  overflow: hidden; clip: rect(0 0 0 0); clip-path: inset(50%); white-space: nowrap;
}
.skip-link:focus, .skip-link:focus-visible {
  position: fixed; top: 12px; left: 12px;
  width: auto; height: auto; margin: 0; clip: auto; clip-path: none;
  background: var(--ink); color: #fff; padding: 10px 18px; border-radius: 10px;
}
:focus-visible { outline: 2.5px solid var(--violet); outline-offset: 3px; border-radius: 2px; }
h1, h2, h3 { font-family: var(--display); font-weight: 700; line-height: 1.22; }
.shell { width: min(100%, var(--maxw)); margin-inline: auto; padding-inline: var(--pad); }

.kicker {
  font-family: var(--mono); font-size: 11px; font-weight: 600;
  letter-spacing: .14em; text-transform: uppercase; color: var(--violet);
  display: inline-flex; align-items: center; gap: 8px;
}
.kicker::before { content: ""; width: 7px; height: 7px; background: var(--coral); border-radius: 50%; flex: none; }
.kicker.plain::before { display: none; }

.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 13px 26px; border: 1.5px solid var(--ink); background: var(--ink); color: #fff;
  font-size: 14px; font-weight: 600; border-radius: 999px;
  transition: background .25s, color .25s, transform .25s, border-color .25s;
}
.btn:hover { background: var(--violet); border-color: var(--violet); transform: translateY(-2px); }
.btn.ghost { background: transparent; color: var(--ink); }
.btn.ghost:hover { background: var(--ink); color: #fff; }
.btn .arr { transition: transform .25s; }
.btn:hover .arr { transform: translateX(4px); }

.text-link {
  font-size: 14px; font-weight: 600; color: var(--violet);
  border-bottom: 1px solid #5e4bd855; padding-bottom: 2px;
  transition: color .2s, border-color .2s;
}
.text-link:hover { color: var(--violet-deep); border-color: var(--violet-deep); }

/* ---------- Header ---------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: #fffffff0; backdrop-filter: blur(14px); -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--line);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; gap: 24px; height: 72px; }
.logo { display: flex; align-items: center; gap: 12px; }
.logo-mark {
  width: 38px; height: 38px; border-radius: 50%; background: var(--ink); color: #fff;
  display: flex; align-items: center; justify-content: center;
  font-family: var(--mono); font-size: 12px; font-weight: 700; letter-spacing: -.02em;
}
.logo-text { font-family: var(--display); font-size: 22px; font-weight: 700; letter-spacing: -.02em; }
.logo-text small { display: block; font-family: var(--mono); font-size: 9px; font-weight: 500; letter-spacing: .16em; color: var(--faint); }
.site-nav { display: flex; align-items: center; gap: clamp(16px, 2.4vw, 32px); }
.site-nav > a {
  font-size: 14px; font-weight: 600; color: var(--ink-soft); padding: 6px 0; position: relative;
}
.site-nav > a::after {
  content: ""; position: absolute; left: 0; right: 0; bottom: 0; height: 2px;
  background: var(--violet); transform: scaleX(0); transform-origin: left; transition: transform .25s;
}
.site-nav > a:hover::after, .site-nav > a.active::after { transform: scaleX(1); }
.site-nav > a.active { color: var(--violet); }
.nav-cta { padding: 9px 20px !important; background: var(--ink); color: #fff !important; border-radius: 999px; font-size: 13px !important; }
.nav-cta::after { display: none; }
.nav-cta:hover { background: var(--violet); }
.nav-toggle { display: none; background: none; border: none; font-size: 22px; cursor: pointer; line-height: 1; padding: 8px; }

/* ---------- Hero (home) ---------- */
.masthead { padding: clamp(36px, 5vw, 64px) 0 0; }
.masthead-top {
  display: flex; align-items: center; justify-content: space-between; gap: 20px;
  padding-bottom: 22px; border-bottom: 1.5px solid var(--line-strong);
  font-family: var(--mono); font-size: 11px; letter-spacing: .12em; color: var(--muted);
}
.masthead h1 {
  font-size: clamp(46px, 7.6vw, 108px); line-height: 1.12; letter-spacing: -.03em;
  margin: clamp(28px, 4vw, 48px) 0 clamp(18px, 2.4vw, 28px);
}
.masthead h1 em { font-style: normal; color: var(--violet); }
.masthead-sub { display: flex; align-items: flex-end; justify-content: space-between; gap: 40px; flex-wrap: wrap; padding-bottom: clamp(32px, 4vw, 52px); border-bottom: 1px solid var(--line); }
.masthead-sub p { max-width: 620px; font-size: clamp(15px, 1.4vw, 18px); color: var(--muted); }
.masthead-actions { display: flex; gap: 14px; flex-wrap: wrap; }

.topic-strip {
  display: flex; gap: 0; overflow-x: auto; border-bottom: 1px solid var(--line);
  scrollbar-width: none;
  -webkit-overflow-scrolling: touch;
  overscroll-behavior-x: contain;
}
.topic-strip::-webkit-scrollbar { display: none; }
.topic-strip a {
  flex: 1 1 0; min-width: 0; justify-content: center;
  padding: 16px 26px; font-size: 14px; font-weight: 600; color: var(--muted);
  border-right: 1px solid var(--line); transition: color .2s, background .2s;
  display: inline-flex; gap: 8px; align-items: center; white-space: nowrap;
}
.topic-strip a:first-child { border-left: 1px solid var(--line); }
.topic-strip a:hover { color: var(--ink); background: var(--surface); }
.topic-strip a small { font-family: var(--mono); font-size: 10px; color: var(--faint); }

/* ---------- Featured story ---------- */
.featured { padding: var(--sec) 0 0; }
.featured-grid {
  display: grid; grid-template-columns: 1.5fr 1fr; gap: 0;
  border: 1.5px solid var(--ink);
}
.featured-main { padding: clamp(28px, 4vw, 52px); display: flex; flex-direction: column; gap: 18px; }
.story-tag { font-family: var(--mono); font-size: 11px; letter-spacing: .12em; color: var(--violet); font-weight: 600; }
.featured-main h2 { font-size: clamp(30px, 3.6vw, 52px); line-height: 1.18; letter-spacing: -.02em; }
.featured-main h2 a:hover { color: var(--violet); }
.featured-main p { color: var(--muted); font-size: 16px; max-width: 560px; }
.featured-art { min-height: 220px; border-top: 1.5px solid var(--ink); margin: 22px calc(-1 * clamp(28px, 4vw, 52px)) calc(-1 * clamp(28px, 4vw, 52px)); }
.featured-side { display: flex; flex-direction: column; border-left: 1.5px solid var(--ink); }
.featured-side a {
  flex: 1; padding: clamp(24px, 3vw, 36px); display: flex; flex-direction: column; gap: 10px;
  border-bottom: 1.5px solid var(--ink); transition: background .25s;
}
.featured-side a:last-child { border-bottom: none; }
.featured-side a:hover { background: var(--surface); }
.featured-side h3 { font-size: 21px; line-height: 1.35; }
.featured-side p { font-size: 13.5px; color: var(--muted); }
.side-more { margin-top: auto; font-family: var(--mono); font-size: 11px; letter-spacing: .1em; color: var(--violet); }

/* CSS 生成封面图 */
.art { position: relative; overflow: hidden; }
.art-violet { background: linear-gradient(160deg, #8f84ec, #6a5bd8 60%, #5446c4); }
.art-violet::after {
  content: ""; position: absolute; width: 46%; aspect-ratio: 1; border-radius: 50%;
  border: 2px solid #141414; top: 18%; left: 30%;
}
.art-violet::before {
  content: ""; position: absolute; width: 72%; aspect-ratio: 1; border-radius: 50%;
  border: 1.5px solid #14141455; top: 2%; left: 16%;
}
.art-lime { background: var(--lime); }
.art-lime::after {
  content: ""; position: absolute; inset: 0;
  background: repeating-linear-gradient(90deg, transparent 0 34px, #141414 34px 36px);
  opacity: .9;
}
.art-coral { background: linear-gradient(150deg, #ec8a68, #df6d59 55%, #d45240); }
.art-coral::after {
  content: ""; position: absolute; width: 140%; height: 16px; background: var(--ink);
  top: 30%; left: -20%; transform: rotate(28deg); transform-origin: left;
}
.art .art-num {
  position: absolute; left: 18px; bottom: 14px; z-index: 2;
  font-family: var(--mono); font-size: 12px; font-weight: 700; color: #141414;
  background: #ffffffcc; padding: 3px 9px;
}

/* ---------- Section head ---------- */
.sec-head {
  display: flex; align-items: flex-end; justify-content: space-between; gap: 28px;
  margin-bottom: clamp(30px, 4vw, 52px); flex-wrap: wrap;
}
.sec-head h2 { font-size: clamp(30px, 4vw, 54px); line-height: 1.16; letter-spacing: -.02em; margin-top: 16px; }
.sec-head p { max-width: 380px; color: var(--muted); font-size: 15px; }
section { padding: var(--sec) 0; }
section + section { border-top: 1px solid var(--line); }
section.flush { border-top: none; }

/* ---------- Article feed ---------- */
.feed { display: flex; flex-direction: column; }
.feed-item {
  display: grid; grid-template-columns: 90px 150px 1fr auto; gap: 24px; align-items: center;
  padding: 26px 0; border-bottom: 1px solid var(--line); transition: background .2s;
}
.feed-item:hover { background: var(--surface); }
.feed-item:hover .feed-title { color: var(--violet); }
.feed-cat { font-family: var(--mono); font-size: 11px; letter-spacing: .1em; color: var(--violet); font-weight: 600; }
.feed-sub { font-size: 12px; color: var(--faint); font-family: var(--mono); }
.feed-title { font-size: clamp(18px, 1.8vw, 24px); line-height: 1.35; font-family: var(--display); font-weight: 700; transition: color .2s; }
.feed-desc { font-size: 13.5px; color: var(--muted); margin-top: 6px; max-width: 640px; }
.feed-arr { font-size: 20px; color: var(--faint); transition: transform .2s, color .2s; padding-right: 8px; }
.feed-item:hover .feed-arr { transform: translateX(6px); color: var(--violet); }

/* ---------- Card grid ---------- */
.card-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.story-card {
  border: 1.5px solid var(--ink); background: var(--paper); display: flex; flex-direction: column;
  transition: transform .3s, box-shadow .3s;
}
.story-card:hover { transform: translateY(-6px); box-shadow: 8px 8px 0 var(--ink); }
.story-card .art { height: 190px; border-bottom: 1.5px solid var(--ink); }
.story-card-body { padding: 24px; display: flex; flex-direction: column; gap: 12px; flex: 1; }
.story-card h3 { font-size: 20px; line-height: 1.35; }
.story-card p { font-size: 14px; color: var(--muted); }
.story-card .more { margin-top: auto; font-family: var(--mono); font-size: 11px; letter-spacing: .1em; color: var(--violet); }

/* ---------- 深色品牌区 ---------- */
.dark-sec { background: var(--dark); color: #f2f2ee; }
.dark-sec .kicker { color: var(--lime); }
.dark-sec .sec-head p { color: var(--dark-muted); }
.brand-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 0; border: 1px solid var(--dark-line); }
.brand-card {
  padding: clamp(28px, 3.4vw, 44px); border-right: 1px solid var(--dark-line);
  display: flex; flex-direction: column; gap: 16px; position: relative; overflow: hidden;
  transition: background .3s;
}
.brand-card:last-child { border-right: none; }
.brand-card:hover { background: var(--dark-2); }
.brand-card .brand-no { font-family: var(--mono); font-size: 11px; letter-spacing: .14em; color: var(--dark-muted); }
.brand-card img.brand-logo { width: 72px; height: 72px; border-radius: 18px; }
.brand-card h3 { font-size: 27px; }
.brand-card h3 span { font-family: var(--mono); font-size: 14px; color: var(--lime); letter-spacing: .06em; }
.brand-card .brand-pos { font-size: 13px; color: var(--coral); font-weight: 600; }
.brand-card p { font-size: 14px; color: var(--dark-muted); }
.brand-card .brand-foot { margin-top: auto; display: flex; align-items: center; justify-content: space-between; gap: 12px; padding-top: 18px; }
.brand-card .brand-foot img { width: 74px; height: 74px; background: #fff; padding: 4px; }
.brand-card .brand-foot span { font-family: var(--mono); font-size: 10.5px; color: var(--dark-muted); letter-spacing: .08em; }
.brand-card::after {
  content: "↗"; position: absolute; top: 24px; right: 26px; font-size: 20px; color: var(--dark-muted);
  transition: transform .25s, color .25s;
}
.brand-card:hover::after { transform: translate(3px, -3px); color: var(--lime); }

/* ---------- 智库 ---------- */
.tank-strip { display: grid; grid-template-columns: repeat(5, 1fr); border: 1.5px solid var(--ink); }
.tank-sector {
  padding: 26px 22px; border-right: 1.5px solid var(--ink); display: flex; flex-direction: column; gap: 8px;
  transition: background .25s, color .25s;
}
.tank-sector:last-child { border-right: none; }
.tank-sector small { font-family: var(--mono); font-size: 10px; letter-spacing: .14em; color: var(--muted); }
.tank-sector b { font-family: var(--display); font-size: 22px; font-weight: 700; }
.tank-sector span { font-size: 13px; color: var(--muted); }
.tank-sector:hover { background: var(--ink); color: #fff; }
.tank-sector:hover small, .tank-sector:hover span { color: #ffffff99; }

.product-list { border-top: 1.5px solid var(--ink); margin-top: 40px; }
.product-row {
  display: grid; grid-template-columns: 130px 90px 1fr 200px 40px; gap: 20px; align-items: center;
  padding: 20px 0; border-bottom: 1px solid var(--line); transition: background .2s;
}
.product-row:hover { background: var(--surface); }
.product-row .vendor { font-family: var(--mono); font-size: 11px; letter-spacing: .08em; color: var(--muted); }
.product-row .date { font-family: var(--mono); font-size: 11px; color: var(--faint); }
.product-row .name { font-family: var(--display); font-size: 20px; font-weight: 700; }
.product-row .name small { display: block; font-family: var(--sans); font-size: 12.5px; font-weight: 400; color: var(--muted); margin-top: 2px; }
.product-row .cat { font-size: 12.5px; color: var(--violet); font-weight: 600; }
.product-row .go { color: var(--faint); font-size: 17px; }

/* ---------- CTA 带 ---------- */
.cta-band { background: var(--lime); color: var(--ink); }
.cta-band .shell { display: flex; align-items: center; justify-content: space-between; gap: 40px; flex-wrap: wrap; }
.cta-band h2 { font-size: clamp(30px, 4.4vw, 60px); line-height: 1.16; letter-spacing: -.02em; max-width: 640px; }
.cta-band p { max-width: 420px; color: #33420cdd; font-size: 15px; margin-top: 14px; }
.cta-band .btn { border-color: var(--ink); }
.cta-band .btn:hover { background: var(--ink); color: var(--lime); }

/* ---------- Footer ---------- */
.site-footer { background: var(--dark); color: var(--dark-muted); font-size: 13.5px; }
.footer-grid { display: grid; grid-template-columns: 1.6fr 1fr 1fr 1fr; gap: 40px; padding: clamp(48px, 6vw, 80px) 0 40px; }
.footer-grid h4 { color: #fff; font-size: 13px; font-family: var(--mono); letter-spacing: .12em; margin-bottom: 18px; font-weight: 600; }
.footer-grid ul { list-style: none; display: grid; gap: 11px; }
.footer-grid a:hover { color: #fff; }
.footer-brand .logo-text { color: #fff; }
.footer-brand .logo-mark { background: #fff; color: var(--dark); }
.footer-desc { margin-top: 18px; max-width: 300px; line-height: 1.9; }
.footer-bar { border-top: 1px solid var(--dark-line); padding: 24px 0 34px; display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; font-size: 12px; font-family: var(--mono); letter-spacing: .04em; }

/* ---------- 内页通用 ---------- */
.page-hero { padding: clamp(36px, 5vw, 64px) 0 clamp(36px, 4.5vw, 56px); }
.page-hero h1 { font-size: clamp(44px, 7vw, 96px); line-height: 1.12; letter-spacing: -.03em; margin: 20px 0 22px; }
.page-hero h1 em { font-style: normal; color: var(--violet); }
.page-hero .lead { max-width: 640px; color: var(--muted); font-size: clamp(15px, 1.4vw, 18px); }
.page-hero .meta-row { display: flex; gap: 18px; align-items: center; margin-top: 30px; flex-wrap: wrap; }

.crumb { font-family: var(--mono); font-size: 11px; letter-spacing: .1em; color: var(--muted); }
.crumb a { color: var(--violet); }
.crumb a:hover { text-decoration: underline; }

/* 文章页 */
.article-grid { display: grid; grid-template-columns: 1fr 320px; gap: clamp(36px, 5vw, 80px); padding: 0 0 var(--sec); }
.article-body .lead-para { font-family: var(--display); font-size: clamp(19px, 1.8vw, 23px); line-height: 1.7; padding: 26px 0; border-top: 1.5px solid var(--ink); border-bottom: 1px solid var(--line); margin-bottom: 40px; }
.article-body h2 { font-size: 28px; margin: 44px 0 16px; }
.article-body p { color: var(--ink-soft); font-size: 16.5px; margin-bottom: 18px; max-width: 700px; }
.article-side { position: sticky; top: 100px; align-self: start; border: 1.5px solid var(--ink); padding: 26px; display: grid; gap: 0; }
.article-side h4 { font-family: var(--mono); font-size: 11px; letter-spacing: .14em; color: var(--violet); margin-bottom: 14px; }
.article-side > p { font-size: 13px; color: var(--muted); padding-bottom: 18px; margin-bottom: 18px; border-bottom: 1px solid var(--line); }
.article-side a { display: flex; justify-content: space-between; padding: 12px 0; font-size: 13.5px; font-weight: 600; border-bottom: 1px solid var(--line); }
.article-side a:last-child { border-bottom: none; }
.article-side a:hover { color: var(--violet); }
.article-nav { display: grid; grid-template-columns: 1fr 1fr; border: 1.5px solid var(--ink); margin-bottom: var(--sec); }
.article-nav a { padding: 24px 28px; display: grid; gap: 6px; }
.article-nav a + a { border-left: 1.5px solid var(--ink); text-align: right; }
.article-nav a:hover { background: var(--surface); }
.article-nav small { font-family: var(--mono); font-size: 10.5px; letter-spacing: .12em; color: var(--faint); }
.article-nav b { font-family: var(--display); font-size: 18px; line-height: 1.4; }
.article-nav a:only-child { grid-column: 1 / -1; }

/* 话题页 */
.faq-list { display: grid; gap: 0; border-top: 1.5px solid var(--ink); }
.faq-item { border-bottom: 1px solid var(--line); padding: 26px 0; display: grid; grid-template-columns: 48px 1fr; gap: 18px; }
.faq-item .n { font-family: var(--mono); font-size: 12px; color: var(--violet); font-weight: 700; padding-top: 5px; }
.faq-item h3 { font-size: 20px; margin-bottom: 8px; }
.faq-item p { color: var(--muted); font-size: 14.5px; max-width: 680px; }
.tag-row { display: flex; gap: 10px; flex-wrap: wrap; }
.tag-row span { font-size: 12.5px; font-weight: 600; border: 1px solid var(--line-strong); border-radius: 999px; padding: 7px 16px; }

/* 品牌内页 */
.brand-hero-grid { display: grid; grid-template-columns: 1fr 300px; gap: clamp(36px, 5vw, 90px); align-items: end; }
.brand-hero-grid img.brand-logo-lg { width: 96px; height: 96px; border-radius: 24px; margin-bottom: 26px; }
.qr-box { border: 1.5px solid var(--ink); padding: 22px; text-align: center; display: grid; gap: 12px; justify-items: center; }
.qr-box img { width: 170px; height: 170px; }
.qr-box span { font-family: var(--mono); font-size: 11px; letter-spacing: .1em; color: var(--muted); }
.qr-box b { font-size: 14px; }

/* 视频频道 */
.channel-row {
  display: grid; grid-template-columns: 220px 1fr 1.2fr; gap: 28px; padding: 30px 0;
  border-bottom: 1px solid var(--line); align-items: start;
}
.channel-row .plat { display: flex; gap: 14px; align-items: baseline; }
.channel-row .plat .idx { font-family: var(--mono); font-size: 11px; color: var(--violet); }
.channel-row .plat h3 { font-size: 26px; }
.channel-row .plat small { display: block; font-family: var(--mono); font-size: 10px; letter-spacing: .14em; color: var(--faint); margin-top: 4px; }
.channel-row > p { color: var(--muted); font-size: 14px; }
.account-list { display: grid; gap: 10px; }
.account-item {
  display: flex; align-items: center; justify-content: space-between; gap: 14px;
  border: 1px solid var(--line); padding: 13px 18px; background: var(--surface);
  transition: border-color .2s, background .2s;
}
.account-item:hover { border-color: var(--ink); background: #fff; }
.account-item b { font-size: 14.5px; display: block; }
.account-item small { color: var(--faint); font-size: 12px; }
.account-item .go { font-family: var(--mono); font-size: 11px; color: var(--violet); white-space: nowrap; }

/* 服务明细表 */
.svc-table { display: grid; grid-template-columns: repeat(5, 1fr); border: 1.5px solid var(--ink); }
.svc-col { padding: 24px 20px; border-right: 1.5px solid var(--ink); display: flex; flex-direction: column; gap: 14px; }
.svc-col:last-child { border-right: none; }
.svc-col h3 { font-size: 17px; padding-bottom: 12px; border-bottom: 1px solid var(--line); }
.svc-col dl { display: grid; gap: 12px; }
.svc-col dt { font-family: var(--mono); font-size: 10px; letter-spacing: .12em; color: var(--violet); font-weight: 700; }
.svc-col dd { font-size: 12.5px; color: var(--muted); line-height: 1.65; margin: 0; }

/* 深色流程区 */
.flow-sec { background: var(--dark); color: #f2f2ee; }
.flow-sec .sec-head p { color: var(--dark-muted); }
.flow-grid { display: grid; grid-template-columns: repeat(4, 1fr); border: 1px solid var(--dark-line); }
.flow-step { padding: 30px 26px; border-right: 1px solid var(--dark-line); display: grid; gap: 12px; align-content: start; }
.flow-step:last-child { border-right: none; }
.flow-step .n { font-family: var(--mono); font-size: 12px; color: var(--lime); letter-spacing: .1em; }
.flow-step h3 { font-size: 19px; }
.flow-step p { font-size: 13px; color: var(--dark-muted); }

/* 分类过滤条 */
.filter-bar { display: flex; gap: 10px; flex-wrap: wrap; padding: 22px 0; border-block: 1px solid var(--line); margin-bottom: 12px; }
.filter-bar button {
  border: 1px solid var(--line-strong); background: transparent; border-radius: 999px;
  padding: 8px 18px; font-size: 13px; font-weight: 600; cursor: pointer; font-family: var(--sans);
  transition: background .2s, color .2s;
}
.filter-bar button:hover { background: var(--surface-2); }
.filter-bar button.on { background: var(--ink); color: #fff; }

/* 动效 */
/* 仅在 JS 可用时才先隐藏，保证无 JS / 搜索引擎渲染时内容始终可见 */
.reveal { transition: opacity .6s cubic-bezier(.2,.7,.3,1), transform .6s cubic-bezier(.2,.7,.3,1); }
html.js .reveal:not(.in) { opacity: 0; transform: translateY(18px); }
@media (prefers-reduced-motion: reduce) {
  .reveal { transition: none; }
  html.js .reveal:not(.in) { opacity: 1; transform: none; }
  html { scroll-behavior: auto; }
}

/* ---------- 网格工具类（替代内联 columns） ---------- */
.cols-2, .cols-3, .cols-4, .cols-5 { display: grid; }
.cols-2 { grid-template-columns: repeat(2, 1fr); }
.cols-3 { grid-template-columns: repeat(3, 1fr); }
.cols-4 { grid-template-columns: repeat(4, 1fr); }
.cols-5 { grid-template-columns: repeat(5, 1fr); }

/* ---------- 响应式 ---------- */
@media (max-width: 1020px) {
  .featured-grid { grid-template-columns: 1fr; }
  .featured-side { border-left: none; border-top: 1.5px solid var(--ink); }
  .card-grid { grid-template-columns: 1fr 1fr; }
  .brand-grid { grid-template-columns: 1fr; }
  .brand-card { border-right: none; border-bottom: 1px solid var(--dark-line); }
  .tank-strip { grid-template-columns: repeat(2, 1fr); }
  .tank-sector { border-bottom: 1.5px solid var(--ink); }
  .tank-sector:nth-child(2n) { border-right: none; }
  .article-grid { grid-template-columns: 1fr; }
  .article-side { position: static; }
  .channel-row { grid-template-columns: 1fr; gap: 14px; }
  .svc-table { grid-template-columns: 1fr 1fr; }
  .svc-col { border-bottom: 1.5px solid var(--ink); }
  .flow-grid { grid-template-columns: 1fr 1fr; }
  .flow-step { border-bottom: 1px solid var(--dark-line); }
  .brand-hero-grid { grid-template-columns: 1fr; }
}
@media (max-width: 720px) {
  .site-nav {
    display: none; position: absolute; top: 72px; left: 0; right: 0;
    flex-direction: column; align-items: stretch; gap: 0;
    background: #fff; border-bottom: 1.5px solid var(--ink); padding: 8px 0;
  }
  .site-nav.open { display: flex; }
  .site-nav > a { padding: 14px 24px; border-top: 1px solid var(--line); }
  .nav-cta { margin: 12px 24px; text-align: center; }
  .nav-toggle { display: block; }
  .feed-item { grid-template-columns: 1fr auto; }
  .feed-cat, .feed-sub { display: none; }
  .card-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 30px; }
  .article-nav { grid-template-columns: 1fr; }
  .article-nav a + a { border-left: none; border-top: 1.5px solid var(--ink); text-align: left; }
  .product-row { grid-template-columns: 1fr auto; }
  .product-row .vendor, .product-row .date, .product-row .cat { display: none; }
  .faq-item { grid-template-columns: 1fr; gap: 4px; }
  .faq-item .n { padding-top: 0; }
  .svc-table { grid-template-columns: 1fr; }
  .masthead-top { flex-direction: column; align-items: flex-start; gap: 6px; }
}

@media (max-width: 1020px) {
  .cols-5, .cols-4, .cols-3 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 720px) {
  .cols-2, .cols-3, .cols-4, .cols-5 { grid-template-columns: 1fr; }
}

/* 频道条：小屏恢复横向滑动 + 边缘渐隐提示 */
@media (max-width: 1020px) {
  .topic-strip a { flex: none; justify-content: flex-start; }
  .topic-strip {
    -webkit-mask-image: linear-gradient(to right, #000 88%, transparent);
    mask-image: linear-gradient(to right, #000 88%, transparent);
  }
}