/* ARC SILICONE — shared design system
   工程图纸风：1px 线、零圆角、零阴影、零渐变；灰度层级只靠线的深浅与位置。
   变量沿用站点主色体系，工程色 --graphite 即 --brand。 */

:root {
  /* brand system */
  --brand: #33465c;
  --brand-strong: #172331;
  --brand-soft: #eef0f2;
  --accent: #1e2328;
  --surface: #f6f7f9;
  --bg: #ffffff;
  --ink: #1d232b;
  --muted: #636f7e;
  --line: #dce0e5;

  /* four greys */
  --t-ink: #1e2328;
  --t-steel: #4a545e;
  --t-mid: #5f6a75;
  --t-mute: #66717c;
  --graphite: #33465c;
  --char: #2b3138;
  --line-2: #dce2e7;
  --panel: #f7f8fa;

  --latin: Bahnschrift, "DIN Alternate", "Segoe UI", Inter, Arial, sans-serif;
  --pad: clamp(20px, 6.25vw, 90px);
  --page: 1440px;
}

* { box-sizing: border-box; }

html {
  background: #e9ecee;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: var(--latin);
  font-size: 14px;
  line-height: 1.6;
  color: var(--t-ink);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4, p, figure, blockquote { margin: 0; }
ul, ol { margin: 0; padding: 0; }
li { list-style: none; }
img { display: block; max-width: 100%; height: auto; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; background: none; border: 0; padding: 0; cursor: pointer; }

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

::selection { background: var(--brand-soft); }

.skip {
  position: absolute;
  left: -9999px;
  top: 0;
  z-index: 9999;
  background: var(--t-ink);
  color: #fff;
  padding: 10px 16px;
  font-size: 12px;
  letter-spacing: .08em;
}

.skip:focus { left: var(--pad); top: 8px; }

.page {
  width: 100%;
  max-width: var(--page);
  margin: 0 auto;
  background: #fff;
  overflow: clip;
}

.pad { padding-left: var(--pad); padding-right: var(--pad); }
.hair { height: 1px; background: var(--line); }

/* ---------- header ---------- */
.hdr {
  padding: 0 var(--pad);
  position: relative;
  background: #fff;
}

.navrow {
  height: 84px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand { display: block; flex: none; }

.brand-mark {
  display: block;
  width: 112px;
  height: 69.7px;
  position: relative;
  overflow: hidden;
}

.brand-mark img {
  position: absolute;
  width: 138.7px;
  height: 102.2px;
  left: -12.2px;
  top: -16.6px;
}

nav.nav {
  display: flex;
  align-items: center;
  gap: 26px;
  font-size: 14px;
  letter-spacing: .06em;
  text-transform: uppercase;
  color: var(--t-steel);
}

nav.nav a {
  position: relative;
  padding-bottom: 2px;
  transition: color .18s ease;
}

nav.nav a:hover { color: var(--t-ink); }
nav.nav a.on { color: var(--t-ink); }

nav.nav a.on::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -4px;
  height: 1px;
  background: var(--t-ink);
}

nav.nav i {
  display: block;
  width: 1px;
  height: 14px;
  background: #c6cdd4;
}

nav.nav .q {
  border: 1px solid #c0c8d0;
  color: var(--t-ink);
  padding: 11px 18px;
  letter-spacing: .06em;
  font-size: 13.5px;
  transition: background-color .18s ease, border-color .18s ease, color .18s ease;
}

nav.nav .q:hover { background: var(--t-ink); color: #fff; border-color: var(--t-ink); }

.nav-toggle {
  display: none;
  border: 1px solid #c0c8d0;
  padding: 9px 14px;
  font-size: 12px;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--t-ink);
  transition: background-color .18s ease, color .18s ease;
}

.nav-toggle:hover { background: var(--t-ink); color: #fff; }

/* ---------- breadcrumb ---------- */
.crumb {
  height: 46px;
  display: flex;
  align-items: center;
  gap: 9px;
  font-size: 12px;
  letter-spacing: .04em;
  color: var(--t-mute);
}

.crumb a { transition: color .18s ease; }
.crumb a:hover { color: var(--t-ink); }
.crumb span { color: #b9c1c8; }
.crumb b { font-weight: 400; color: var(--t-steel); }

/* ---------- hero ---------- */
.hero {
  display: grid;
  grid-template-columns: 1fr 396px;
  gap: 60px;
  padding-top: 44px;
  padding-bottom: 46px;
}

.eyebrow {
  display: flex;
  align-items: center;
  gap: 14px;
  font-size: 11.5px;
  letter-spacing: .19em;
  text-transform: uppercase;
  color: var(--graphite);
  font-weight: 600;
}

.eyebrow b { flex: 1; height: 1px; background: var(--line-2); }

h1 {
  font-size: clamp(34px, 3.7vw, 52px);
  line-height: 1.06;
  letter-spacing: -.03em;
  font-weight: 600;
  margin-top: 22px;
}

.lede {
  margin-top: 18px;
  font-size: clamp(17px, 1.5vw, 21px);
  line-height: 1.5;
  color: var(--t-steel);
  letter-spacing: -.01em;
}

.sub {
  margin-top: 10px;
  font-size: 14.5px;
  line-height: 1.62;
  color: var(--t-mid);
  max-width: 640px;
}

.sub b { font-weight: 600; color: var(--t-ink); }

.btns { margin-top: 32px; display: flex; gap: 12px; flex-wrap: wrap; }

.btn {
  display: inline-block;
  padding: 14px 24px;
  font-size: 14px;
  letter-spacing: .05em;
  border: 1px solid var(--t-ink);
  transition: background-color .18s ease, color .18s ease, border-color .18s ease;
  cursor: pointer;
}

.b1 { background: var(--t-ink); color: #fff; }
.b1:hover { background: var(--graphite); border-color: var(--graphite); }
.b2 { background: #fff; color: var(--t-ink); }
.b2:hover { background: var(--panel); }
.btn:active { transform: translateY(1px); }
.btn[disabled] { opacity: .55; cursor: not-allowed; }

.btn-note {
  margin-top: 14px;
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--t-mid);
  letter-spacing: .02em;
}

/* ---------- facts panel ---------- */
.hfacts { border-top: 1px solid var(--t-ink); align-self: start; }

.hf {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 16px;
  align-items: baseline;
  padding: 13px 0;
  border-bottom: 1px solid var(--line);
}

.hf u {
  text-decoration: none;
  font-size: 11.5px;
  letter-spacing: .13em;
  text-transform: uppercase;
  color: var(--t-mute);
}

.hf b { font-size: 19px; font-weight: 600; letter-spacing: -.01em; }

.hf b em {
  font-style: normal;
  font-size: 11.5px;
  letter-spacing: .06em;
  color: var(--t-mute);
  font-weight: 400;
  margin-left: 5px;
}

.hnote {
  margin-top: 12px;
  font-size: 11.5px;
  line-height: 1.66;
  color: var(--t-mute);
}

/* ---------- section ---------- */
.sec { padding-top: 56px; }

.sechead {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 24px;
  border-top: 1px solid var(--line);
  padding-top: 14px;
}

.secnum {
  font-size: 11.5px;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--graphite);
  font-weight: 600;
}

.secmeta {
  font-size: 11.5px;
  letter-spacing: .06em;
  color: var(--t-mute);
  text-align: right;
}

.sech {
  margin-top: 16px;
  font-size: clamp(22px, 2vw, 27px);
  line-height: 1.22;
  letter-spacing: -.02em;
  font-weight: 600;
}

.secp {
  margin-top: 12px;
  font-size: 13.5px;
  line-height: 1.7;
  color: var(--t-mid);
  max-width: 980px;
}

.secp b { font-weight: 600; color: var(--t-ink); }
.secp a { border-bottom: 1px solid #c6cdd4; transition: border-color .18s ease, color .18s ease; }
.secp a:hover { color: var(--t-ink); border-color: var(--graphite); }
.secp + .secp { margin-top: 10px; }

/* ---------- dual mode cards ---------- */
.duo { margin-top: 24px; display: grid; grid-template-columns: 1fr 1fr; gap: 22px; }

.mode {
  border: 1px solid var(--line);
  padding: 22px 24px 20px;
  display: flex;
  flex-direction: column;
  transition: border-color .2s ease;
}

.mode:hover { border-color: #b9c1c8; }

.mtag {
  font-size: 11.5px;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--graphite);
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 12px;
}

.mtag em {
  font-style: normal;
  font-size: 11.5px;
  letter-spacing: .06em;
  color: var(--t-mute);
  font-weight: 400;
  text-transform: none;
}

.mode h3 { margin-top: 9px; font-size: 19px; font-weight: 600; letter-spacing: -.012em; }
.mode p { margin-top: 9px; font-size: 13px; line-height: 1.66; color: var(--t-mid); flex: 1; }
.mode p b { font-weight: 600; color: var(--t-ink); }

.mfoot {
  flex: 0 0 auto;
  margin-top: 14px;
  padding-top: 12px;
  border-top: 1px solid var(--line);
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--t-mute);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

.mode p.mfoot { flex: 0 0 auto; }

.mfoot b { font-weight: 600; color: var(--graphite); }
.mfoot a { border-bottom: 1px solid #c6cdd4; transition: color .18s ease, border-color .18s ease; }
.mfoot a:hover { color: var(--t-ink); border-color: var(--graphite); }

/* ---------- domain rows ---------- */
.rows { margin-top: 24px; border-top: 1px solid var(--line); }

.row {
  display: grid;
  grid-template-columns: 56px 250px 1fr 190px;
  border-bottom: 1px solid var(--line);
  align-items: center;
  padding: 15px 0;
  transition: background-color .18s ease;
}

.row:hover { background: #fbfcfd; }

.row .no {
  font-size: 11px;
  letter-spacing: .14em;
  color: var(--graphite);
  font-weight: 600;
}

.row h3 { font-size: 16px; font-weight: 600; letter-spacing: -.01em; }
.row p { font-size: 12.5px; line-height: 1.55; color: var(--t-mid); padding-right: 30px; }

.row .go {
  font-size: 11.5px;
  letter-spacing: .09em;
  text-transform: uppercase;
  color: var(--graphite);
  display: flex;
  align-items: center;
  gap: 8px;
  justify-content: flex-end;
  transition: gap .18s ease, color .18s ease;
}

.row:hover .go { gap: 14px; }

/* ---------- stat strip ---------- */
.stats {
  margin-top: 26px;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  border-top: 1px solid var(--t-ink);
  border-bottom: 1px solid var(--line);
}

.st { padding: 20px 22px 22px; }
.st + .st { border-left: 1px solid var(--line); }
.st b { display: block; font-size: clamp(28px, 2.6vw, 34px); font-weight: 600; letter-spacing: -.03em; }

.st b em {
  font-style: normal;
  font-size: 13px;
  letter-spacing: .04em;
  color: var(--t-mute);
  margin-left: 5px;
  font-weight: 400;
}

.st span { display: block; margin-top: 8px; font-size: 12px; line-height: 1.6; color: var(--t-mid); }

/* ---------- steps ---------- */
.steps { margin-top: 26px; display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }

.step {
  border: 1px solid var(--line);
  padding: 20px 22px;
  display: flex;
  flex-direction: column;
  transition: border-color .2s ease;
}

.step:hover { border-color: #b9c1c8; }

.step u {
  text-decoration: none;
  font-size: 11px;
  letter-spacing: .16em;
  color: var(--graphite);
  font-weight: 600;
  text-transform: uppercase;
}

.step h3 { margin-top: 10px; font-size: 17px; font-weight: 600; letter-spacing: -.01em; }
.step p { margin-top: 9px; font-size: 12.5px; line-height: 1.62; color: var(--t-mid); flex: 1; }

.step .rep {
  flex: 0 0 auto;
  margin-top: 12px;
  padding-top: 10px;
  border-top: 1px solid var(--line);
  font-size: 11.5px;
  letter-spacing: .05em;
  color: var(--t-mute);
}

.step .rep b { color: var(--t-ink); font-weight: 600; }

.step .rep a {
  color: var(--graphite);
  border-bottom: 1px solid #c6cdd4;
  transition: color .18s ease, border-color .18s ease;
}

.step .rep a:hover { color: var(--t-ink); border-color: var(--graphite); }

/* ---------- don't list ---------- */
.dont { margin-top: 24px; border-top: 1px solid var(--line); }

.dont li {
  display: grid;
  grid-template-columns: 230px 1fr;
  gap: 24px;
  padding: 13px 0;
  border-bottom: 1px solid var(--line);
  font-size: 12.5px;
  line-height: 1.62;
}

.dont li b { font-weight: 600; color: var(--t-ink); }
.dont li span { color: var(--t-mid); }

/* ---------- chips ---------- */
.chips { display: flex; flex-wrap: wrap; gap: 6px; }

.chip {
  border: 1px solid #c6cdd4;
  background: #fff;
  padding: 3.5px 8px;
  font-size: 11px;
  line-height: 1.35;
  color: var(--t-steel);
  white-space: nowrap;
  transition: border-color .18s ease, color .18s ease;
}

a.chip:hover, .chip:hover { border-color: var(--graphite); color: var(--t-ink); }

/* ---------- tables ---------- */
.tbl { margin-top: 24px; border-top: 1px solid var(--t-ink); }
.thead, .trow { display: grid; border-bottom: 1px solid var(--line); }

.thead {
  background: var(--panel);
  font-size: 11.5px;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--t-mute);
}

.thead span, .trow span, .trow b { padding: 12px 18px 12px 0; }
.trow { font-size: 12.5px; line-height: 1.62; color: var(--t-mid); }
.trow b { font-weight: 600; color: var(--t-ink); }
.trow em { font-style: normal; color: var(--graphite); font-weight: 600; }

.tnote {
  margin-top: 12px;
  font-size: 11.5px;
  line-height: 1.66;
  color: var(--t-mute);
  max-width: 900px;
}

.tnote b { font-weight: 600; color: var(--t-steel); }

/* ---------- aside list (what comes back / what you get) ---------- */
.back { margin-top: 12px; border-top: 1px solid var(--t-ink); }

.back li {
  display: grid;
  grid-template-columns: 116px 1fr;
  gap: 16px;
  padding: 11px 0;
  border-bottom: 1px solid var(--line);
  font-size: 12px;
  line-height: 1.6;
  color: var(--t-mid);
}

.back li b {
  font-size: 10.5px;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--graphite);
  font-weight: 600;
  padding-top: 2px;
}

/* ---------- CTA ---------- */
.cta {
  margin-top: 64px;
  border-top: 1px solid var(--t-ink);
  display: grid;
  grid-template-columns: 1fr 1fr;
  padding-bottom: 8px;
}

.cta > div {
  padding: 30px 0 34px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.cta > div + div { border-left: 1px solid var(--line); padding-left: 44px; }

.cta u {
  text-decoration: none;
  font-size: 11px;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--graphite);
  font-weight: 600;
}

.cta b { font-size: clamp(21px, 1.9vw, 25px); font-weight: 600; letter-spacing: -.02em; line-height: 1.28; }
.cta p { font-size: 13px; line-height: 1.62; color: var(--t-mid); }

.cta .go {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 11.5px;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--graphite);
  margin-top: 2px;
  transition: gap .18s ease, color .18s ease;
}

.cta .go:hover { gap: 16px; color: var(--t-ink); }

/* ---------- footer ---------- */
footer {
  margin-top: 70px;
  background: var(--t-ink);
  color: #c9d2da;
  padding: 42px var(--pad) 26px;
}

.fgrid { display: grid; grid-template-columns: 1.5fr 1fr 1fr 1fr; gap: 40px; }

.fbrand b { display: block; color: #fff; font-size: 15px; letter-spacing: .14em; }
.fbrand p { margin-top: 12px; font-size: 11.5px; line-height: 1.8; color: #96a1ac; }
.fbrand a { transition: color .18s ease; }
.fbrand a:hover { color: #fff; }

.fcol u {
  text-decoration: none;
  display: block;
  font-size: 11px;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: #7e8b97;
  margin-bottom: 12px;
}

.fcol li { font-size: 12px; line-height: 2; color: #c9d2da; }

.fcol a {
  display: inline-block;
  transition: color .18s ease, transform .18s ease;
}

.fcol a:hover { color: #fff; transform: translateX(2px); }

.fbot {
  margin-top: 34px;
  padding-top: 16px;
  border-top: 1px solid #333b42;
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 20px;
  flex-wrap: wrap;
  font-size: 10.5px;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: #7e8b97;
}

.fbot a { color: #aab4be; transition: color .18s ease; }
.fbot a:hover { color: #fff; }
.fbot .crawl { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }

/* ---------- forms ---------- */
.field { display: flex; flex-direction: column; gap: 6px; }
.field label { font-size: 11px; letter-spacing: .14em; text-transform: uppercase; color: var(--t-mute); }
.field label i { font-style: normal; color: var(--graphite); margin-left: 3px; }

.field input,
.field select,
.field textarea {
  width: 100%;
  font: inherit;
  font-size: 13px;
  color: var(--t-ink);
  background: #fff;
  border: 1px solid #c6cdd4;
  border-radius: 0;
  padding: 10px 12px;
  transition: border-color .18s ease, box-shadow .18s ease;
}

.field input:hover,
.field select:hover,
.field textarea:hover { border-color: #9aa5b0; }

.field input:focus,
.field select:focus,
.field textarea:focus {
  outline: none;
  border-color: var(--graphite);
  box-shadow: inset 0 0 0 1px var(--graphite);
}

.field textarea { min-height: 92px; resize: vertical; }

.field select {
  appearance: none;
  border-radius: 0;
  background-image: linear-gradient(45deg, transparent 50%, #5f6a75 50%), linear-gradient(135deg, #5f6a75 50%, transparent 50%);
  background-position: calc(100% - 17px) 18px, calc(100% - 12px) 18px;
  background-size: 5px 5px, 5px 5px;
  background-repeat: no-repeat;
}

.form-status {
  margin-top: 12px;
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--t-steel);
  min-height: 20px;
}

.form-status.is-ok { color: #1f5c3f; }
.form-status.is-err { color: #9a2f2f; }

/* ---------- reveal (JS only) ---------- */
html.js [data-reveal] {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity .4s ease, transform .4s ease;
}

html.js [data-reveal].is-in { opacity: 1; transform: none; }

/* ---------- responsive ---------- */
@media (max-width: 1180px) {
  .hero { grid-template-columns: 1fr 320px; gap: 40px; }
  .fgrid { grid-template-columns: 1fr 1fr; gap: 32px; }
}

@media (max-width: 980px) {
  .nav-toggle { display: inline-block; }

  nav.nav {
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    top: 84px;
    z-index: 40;
    flex-direction: column;
    align-items: flex-start;
    gap: 0;
    background: #fff;
    border-top: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
    padding: 8px var(--pad) 18px;
  }

  .hdr.is-open nav.nav { display: flex; }
  nav.nav a { padding: 12px 0; width: 100%; }
  nav.nav a.on::after { bottom: 6px; right: auto; width: 22px; }
  nav.nav i { display: none; }
  nav.nav .q { margin-top: 10px; text-align: center; }

  .hero { grid-template-columns: 1fr; gap: 34px; padding-top: 30px; padding-bottom: 34px; }
  .stats { grid-template-columns: 1fr 1fr; }
  .st:nth-child(3) { border-left: 0; border-top: 1px solid var(--line); }
  .st:nth-child(4) { border-top: 1px solid var(--line); }
  .steps { grid-template-columns: 1fr; }
  .duo { grid-template-columns: 1fr; }
  .row { grid-template-columns: 40px 1fr; gap: 6px 0; padding: 16px 0; }
  .row p { grid-column: 2; padding-right: 0; margin-top: 4px; }
  .row .go { grid-column: 2; justify-content: flex-start; margin-top: 8px; }
  .dont li { grid-template-columns: 1fr; gap: 2px; }
  .cta { grid-template-columns: 1fr; }
  .cta > div + div { border-left: 0; border-top: 1px solid var(--line); padding-left: 0; }
  .sechead { flex-direction: column; gap: 4px; }
  .secmeta { text-align: left; }
}

@media (max-width: 720px) {
  .thead { display: none; }

  .trow {
    display: block;
    padding: 14px 0;
  }

  .trow > * {
    display: block;
    padding: 0;
    font-size: 12.5px;
    line-height: 1.6;
  }

  .trow > * + * { margin-top: 4px; }

  .trow > *[data-th]::before {
    content: attr(data-th) " · ";
    font-size: 10.5px;
    letter-spacing: .12em;
    text-transform: uppercase;
    color: var(--t-mute);
  }

  .fgrid { grid-template-columns: 1fr; gap: 26px; }
  .fbot { flex-direction: column; align-items: flex-start; gap: 10px; }
  .btns .btn { width: 100%; text-align: center; }
}

@media (prefers-reduced-motion: reduce) {
  html.js [data-reveal],
  html.js [data-reveal].is-in {
    opacity: 1;
    transform: none;
    transition: none;
  }

  *,
  *::before,
  *::after {
    animation-duration: .001ms !important;
    transition-duration: .001ms !important;
  }
}