:root {
  --steel: #1b2c36;
  --steel-2: #243844;
  --line: #4ec4d6;
  --line-dim: #2a6a78;
  --paper: #e8eef1;
  --muted: #6a7c86;
  --cap-blank: #d24a4a;
  --cap-ext: #d2a13a;
  --cap-upd: #4ec4d6;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: auto; }
body {
  font-family: "IBM Plex Sans", "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--steel);
  color: var(--paper);
  line-height: 1.75;
  font-size: 16.5px;
  background-image:
    linear-gradient(rgba(78, 196, 214, 0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(78, 196, 214, 0.06) 1px, transparent 1px);
  background-size: 24px 24px;
}
a { color: inherit; }
.wrap { width: min(1100px, calc(100% - 36px)); margin: 0 auto; }

.mast {
  border-bottom: 1px solid var(--line-dim);
  padding: 14px 0;
  background: #15242c;
}
.mast-row { display: flex; align-items: center; gap: 12px; }
.brand { font-size: 14px; letter-spacing: 0.12em; text-transform: uppercase; color: var(--line); }

.caps {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 16px 0 8px;
}
.cap {
  font-size: 12px;
  letter-spacing: 0.1em;
  border: 1px solid currentColor;
  padding: 3px 10px;
  border-radius: 999px;
}
.cap.blank { color: #f0a0a0; border-color: var(--cap-blank); }
.cap.ext { color: #f0d090; border-color: var(--cap-ext); }
.cap.upd { color: var(--line); border-color: var(--cap-upd); }

.hero { padding: 50px 0 34px; }
h1 { font-size: clamp(26px, 3.6vw, 36px); line-height: 1.35; max-width: 16em; margin-bottom: 16px; }
.hero p { max-width: 46em; margin-bottom: 12px; color: #c5d4da; }

.section {
  padding: 44px 0;
  border-top: 1px solid var(--line-dim);
}
h2 { font-size: clamp(21px, 2.4vw, 27px); line-height: 1.4; margin-bottom: 14px; color: var(--line); max-width: 20em; }
.lead { margin-bottom: 14px; color: #c5d4da; max-width: 48em; }

.polyline {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
  margin: 22px 0 10px;
  position: relative;
}
.polyline::before {
  content: "";
  position: absolute;
  left: 8%;
  right: 8%;
  top: 18px;
  height: 2px;
  background: linear-gradient(90deg, var(--line) 0%, var(--line-dim) 50%, var(--line) 100%);
}
.poly-node { text-align: center; padding-top: 0; position: relative; }
.poly-dot {
  width: 16px;
  height: 16px;
  margin: 10px auto 10px;
  background: var(--steel);
  border: 2px solid var(--line);
  transform: rotate(45deg);
  position: relative;
  z-index: 1;
}
.poly-node p { font-size: 13px; color: #c5d4da; }

.diag-steps { display: grid; gap: 14px; margin-top: 18px; }
.diag-step {
  display: grid;
  grid-template-columns: 72px 1fr;
  gap: 14px;
  border: 1px solid var(--line-dim);
  background: var(--steel-2);
  padding: 14px;
}
.diag-num {
  font-size: 13px;
  color: var(--line);
  letter-spacing: 0.08em;
  border-right: 1px solid var(--line-dim);
  padding-right: 10px;
}
.diag-step h3 { font-size: 17px; margin-bottom: 6px; }
.diag-step p { font-size: 15px; color: #c5d4da; }

.cards { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 12px; margin-top: 16px; }
.card { border: 1px solid var(--line-dim); background: #1f333d; padding: 16px; }
.card h3 { font-size: 16px; margin-bottom: 8px; color: var(--line); }
.card p { font-size: 14px; color: #c5d4da; margin-bottom: 8px; }

.table-wrap { overflow-x: auto; margin-top: 14px; }
table { width: 100%; border-collapse: collapse; background: #1f333d; }
th, td { border: 1px solid var(--line-dim); padding: 10px 12px; text-align: left; font-size: 14.5px; vertical-align: top; }
th { color: var(--line); font-weight: 600; }

.split { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin-top: 14px; }
.split article { border: 1px solid var(--line-dim); background: #1f333d; padding: 16px; }
.split h3 { font-size: 17px; margin-bottom: 8px; color: var(--line); }
.split p { font-size: 15px; color: #c5d4da; margin-bottom: 8px; }

.faq { display: grid; gap: 10px; margin-top: 14px; }
.faq details { border: 1px solid var(--line-dim); background: #1f333d; padding: 12px 14px; }
.faq summary { cursor: pointer; font-weight: 600; color: var(--paper); }
.faq p { margin-top: 8px; font-size: 15px; color: #c5d4da; }

.site-footer {
  border-top: 1px solid var(--line);
  padding: 34px 0 26px;
  font-size: 14px;
  background: #15242c;
  color: #a8bcc4;
}
.site-footer h2 { color: var(--line); font-size: 18px; margin-bottom: 10px; }
.site-footer p { margin-bottom: 10px; max-width: 46em; }
.legal { margin-top: 14px; padding-top: 12px; border-top: 1px solid var(--line-dim); }

@media (max-width: 800px) {
  .polyline, .cards, .split { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 560px) {
  .polyline, .cards, .split, .diag-step { grid-template-columns: 1fr; }
  .diag-num { border-right: 0; border-bottom: 1px solid var(--line-dim); padding-bottom: 8px; }
}

.mast-row { justify-content: space-between; flex-wrap: wrap; }
.mast-nav { display: flex; flex-wrap: wrap; gap: 8px 14px; font-size: 12px; letter-spacing: 0.06em; }
.mast-nav a { color: #4ec4d6; text-decoration: none; }
.mast-nav a:hover { text-decoration: underline; }