/* ============================================================
   Optical Interconnect Knowledge Hub — v2 visual system
   Dark tech theme · refined palette · glass header · glow hero
   ============================================================ */
:root {
  --bg: #050b18;
  --bg-soft: #081226;
  --panel: rgba(15, 28, 58, .55);
  --panel-solid: #0e1c3d;
  --panel-2: #12244c;
  --line: rgba(88, 130, 200, .18);
  --line-strong: rgba(88, 130, 200, .32);
  --text: #d9e4f8;
  --muted: #93a7cc;
  --accent: #38bdf8;
  --accent-2: #22d3ee;
  --accent-3: #818cf8;
  --ink: #04101f;
  --glow: rgba(56, 189, 248, .22);
  --maxw: 900px;
  --radius: 14px;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background:
    radial-gradient(1100px 500px at 85% -100px, rgba(56, 189, 248, .07), transparent 60%),
    radial-gradient(900px 420px at -10% 20%, rgba(129, 140, 248, .05), transparent 55%),
    var(--bg);
  color: var(--text);
  font-family: "Inter", "Segoe UI", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  line-height: 1.75;
  font-size: 16.5px;
  -webkit-font-smoothing: antialiased;
}
body[dir="rtl"] { text-align: right; }
::selection { background: rgba(56, 189, 248, .35); color: #fff; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 6px; }
.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 22px; }

/* ---------------- header ---------------- */
header.site {
  position: sticky; top: 0; z-index: 50;
  background: rgba(5, 11, 24, .78);
  backdrop-filter: blur(14px) saturate(1.4);
  -webkit-backdrop-filter: blur(14px) saturate(1.4);
  border-bottom: 1px solid var(--line);
}
.site-inner {
  max-width: 1160px; margin: 0 auto; padding: 12px 22px;
  display: flex; align-items: center; gap: 16px; flex-wrap: wrap;
}
.logo {
  display: inline-flex; align-items: center; gap: 10px;
  font-weight: 700; font-size: 1rem; color: #fff; letter-spacing: .2px;
  white-space: nowrap; line-height: 1.2;
}
.logo:hover { text-decoration: none; }
.logo .mark { flex: none; display: block; }
.logo .logo-text b {
  background: linear-gradient(90deg, var(--accent), var(--accent-3));
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent; color: var(--accent);
  font-weight: 800;
}
nav.main {
  display: flex; gap: 2px; flex-wrap: nowrap;
  margin-inline-start: auto; overflow-x: auto; max-width: 100%;
  scrollbar-width: none; padding: 2px;
}
nav.main::-webkit-scrollbar { display: none; }
nav.main a {
  color: var(--muted); font-size: .865rem; font-weight: 500;
  padding: 7px 11px; border-radius: 9px; white-space: nowrap;
  transition: color .15s, background .15s;
}
nav.main a:hover { color: #fff; background: rgba(56, 189, 248, .10); text-decoration: none; }
nav.main a.active { color: #fff; background: rgba(56, 189, 248, .16); }
nav.main a.ext {
  color: var(--ink); font-weight: 700; margin-inline-start: 6px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  box-shadow: 0 0 18px rgba(56, 189, 248, .35);
}
nav.main a.ext:hover { filter: brightness(1.1); color: var(--ink); background: linear-gradient(135deg, var(--accent), var(--accent-2)); }
.langs { font-size: .8rem; color: var(--muted); display: flex; flex-wrap: wrap; gap: 1px 4px; max-width: 220px; }
.langs a { color: var(--muted); padding: 0 3px; opacity: .85; }
.langs a:hover { color: #fff; opacity: 1; }
.langs a.on { color: var(--accent); font-weight: 700; opacity: 1; }

/* ---------------- hero ---------------- */
.hero {
  position: relative; overflow: hidden;
  padding: 84px 0 64px;
  border-bottom: 1px solid var(--line);
  background:
    radial-gradient(1000px 380px at 18% -20%, rgba(56, 189, 248, .18), transparent 62%),
    radial-gradient(760px 340px at 82% -5%, rgba(129, 140, 248, .13), transparent 60%),
    linear-gradient(180deg, var(--bg-soft), var(--bg));
}
.hero::before {
  content: ""; position: absolute; inset: 0; pointer-events: none;
  background-image:
    linear-gradient(rgba(88, 130, 200, .07) 1px, transparent 1px),
    linear-gradient(90deg, rgba(88, 130, 200, .07) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: radial-gradient(720px 340px at 50% 0%, #000 30%, transparent 75%);
  -webkit-mask-image: radial-gradient(720px 340px at 50% 0%, #000 30%, transparent 75%);
}
.hero .wrap { position: relative; }
.hero h1 {
  margin: 0 0 16px; color: #fff; line-height: 1.22;
  font-size: clamp(1.9rem, 4.4vw, 2.8rem);
  letter-spacing: -.02em; font-weight: 800;
}
.hero h1 .grad {
  background: linear-gradient(90deg, var(--accent), var(--accent-2) 55%, var(--accent-3));
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
}
.hero p { max-width: 760px; color: var(--muted); margin: 0; font-size: 1.06rem; }
.badge {
  display: inline-flex; align-items: center; gap: 7px; margin-bottom: 20px;
  padding: 5px 14px; border: 1px solid var(--line-strong); border-radius: 999px;
  color: var(--accent-2); font-size: .76rem; font-weight: 600;
  letter-spacing: 1.2px; text-transform: uppercase;
  background: rgba(34, 211, 238, .06);
}
.badge::before { content: ""; width: 6px; height: 6px; border-radius: 50%; background: var(--accent-2); box-shadow: 0 0 10px var(--accent-2); }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 26px; }
a.btn, .cta a.btn {
  display: inline-flex; align-items: center; gap: 8px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: var(--ink); font-weight: 700; padding: 12px 24px;
  border-radius: 12px; font-size: .98rem; line-height: 1.2;
  box-shadow: 0 4px 24px var(--glow);
  transition: transform .15s, box-shadow .15s, filter .15s;
}
a.btn:hover, .cta a.btn:hover { text-decoration: none; filter: brightness(1.1); transform: translateY(-1px); box-shadow: 0 6px 30px rgba(56, 189, 248, .4); }
a.btn.ghost {
  background: rgba(56, 189, 248, .08); color: var(--accent);
  border: 1px solid var(--line-strong); box-shadow: none;
}
a.btn.ghost:hover { background: rgba(56, 189, 248, .14); box-shadow: none; }
.hero-btn { margin-top: 0; }

/* ---------------- cards & grids ---------------- */
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(255px, 1fr)); gap: 16px; margin: 24px 0 48px; }
.card {
  position: relative;
  background: linear-gradient(180deg, rgba(18, 36, 76, .5), rgba(14, 28, 61, .35));
  border: 1px solid var(--line); border-radius: var(--radius);
  padding: 20px; display: flex; flex-direction: column; gap: 8px;
  transition: transform .18s ease, border-color .18s ease, box-shadow .18s ease;
}
.card::after {
  content: "→"; position: absolute; top: 16px; inset-inline-end: 16px;
  color: var(--accent); opacity: 0; transform: translateX(-4px);
  transition: opacity .18s, transform .18s; font-weight: 700;
}
body[dir="rtl"] .card::after { transform: translateX(4px) scaleX(-1); }
.card:hover {
  transform: translateY(-3px); border-color: rgba(56, 189, 248, .55);
  box-shadow: 0 10px 32px rgba(2, 8, 20, .55), 0 0 0 1px rgba(56, 189, 248, .12);
  text-decoration: none;
}
.card:hover::after { opacity: 1; transform: translateX(0); }
.card h3 { margin: 0; font-size: 1.02rem; color: #fff; line-height: 1.45; padding-inline-end: 18px; }
.card p { margin: 0; color: var(--muted); font-size: .86rem; line-height: 1.6; flex: 1; }
.card .meta {
  margin-top: 6px; font-size: .74rem; font-weight: 600; color: var(--accent-2);
  text-transform: uppercase; letter-spacing: .6px;
}
h2.section {
  font-size: 1.3rem; color: #fff; margin: 40px 0 6px;
  letter-spacing: -.01em; font-weight: 750;
  display: flex; align-items: center; gap: 12px;
}
h2.section::before {
  content: ""; flex: none; width: 4px; height: 22px; border-radius: 2px;
  background: linear-gradient(180deg, var(--accent), var(--accent-3));
}

/* ---------------- article ---------------- */
article.post { padding: 48px 0 24px; }
article.post h1 {
  color: #fff; font-size: clamp(1.6rem, 3.6vw, 2.25rem);
  line-height: 1.28; margin: 8px 0 12px; letter-spacing: -.015em; font-weight: 800;
}
.lede { color: var(--muted); font-size: 1.08rem; margin-bottom: 8px; }
.postmeta { color: var(--muted); font-size: .82rem; margin-bottom: 30px; display: flex; flex-wrap: wrap; gap: 4px 10px; align-items: center; }
.postmeta .cat {
  color: var(--accent-2); font-weight: 600; text-transform: uppercase;
  font-size: .74rem; letter-spacing: .8px;
  padding: 3px 10px; border: 1px solid var(--line-strong); border-radius: 999px;
  background: rgba(34, 211, 238, .06);
}
article.post h2 {
  color: #fff; font-size: 1.34rem; margin: 42px 0 14px; padding-top: 22px;
  border-top: 1px solid var(--line); letter-spacing: -.01em; font-weight: 750;
}
article.post h3 { color: #e6efff; font-size: 1.1rem; margin: 28px 0 10px; font-weight: 700; }
article.post p, article.post li { color: var(--text); }
article.post ul, article.post ol { padding-inline-start: 24px; }
article.post li { margin: 7px 0; }
article.post li::marker { color: var(--accent); }
article.post a { border-bottom: 1px solid rgba(56, 189, 248, .35); }
article.post a:hover { border-bottom-color: var(--accent); }
strong { color: #fff; }

/* tables */
.tablewrap { overflow-x: auto; margin: 20px 0 28px; border: 1px solid var(--line); border-radius: 12px; }
article.post table, table {
  border-collapse: collapse; width: 100%; margin: 0; font-size: .92rem;
  background: rgba(10, 20, 44, .5);
}
.tablewrap table { margin: 0; }
table { border: 1px solid var(--line); border-radius: 12px; }
th, td { border: 1px solid var(--line); padding: 10px 14px; text-align: left; vertical-align: top; }
th {
  background: linear-gradient(180deg, var(--panel-2), #0f2044);
  color: #fff; font-weight: 650; white-space: nowrap; font-size: .88rem;
}
td { background: rgba(14, 28, 61, .35); }
tr:nth-child(even) td { background: rgba(8, 18, 38, .55); }
tbody tr { transition: background .12s; }
tbody tr:hover td { background: rgba(56, 189, 248, .07); }

blockquote {
  margin: 20px 0; padding: 14px 20px; border-inline-start: 3px solid var(--accent);
  background: rgba(56, 189, 248, .06); border-radius: 0 12px 12px 0; color: var(--muted);
}
code {
  background: rgba(18, 36, 76, .8); border: 1px solid var(--line);
  border-radius: 6px; padding: 1px 7px; font-size: .87em; color: #9fe0f7;
  font-family: "Cascadia Code", Consolas, "JetBrains Mono", monospace;
}
pre > code { display: block; padding: 14px 16px; overflow-x: auto; background: rgba(8, 18, 38, .8); line-height: 1.6; }
/* mermaid vector diagrams (phase-1 visuals) */
.mermaidwrap {
  margin: 22px 0 28px; border: 1px solid var(--line); border-radius: 12px;
  background: rgba(10, 20, 44, .6); padding: 18px 14px; overflow-x: auto;
}
pre.mermaid {
  margin: 0; display: flex; justify-content: center;
  font-family: "Inter", "Segoe UI", system-ui, sans-serif; font-size: .92rem;
}

/* ---------------- CTA + footer ---------------- */
.cta {
  position: relative; overflow: hidden;
  margin: 48px 0 36px; padding: 26px 28px; border-radius: 16px;
  background:
    radial-gradient(420px 160px at 90% -30%, rgba(56, 189, 248, .16), transparent 65%),
    linear-gradient(135deg, rgba(18, 36, 76, .75), rgba(14, 28, 61, .5));
  border: 1px solid var(--line-strong);
}
.cta h3 { margin: 0 0 8px; color: #fff; font-size: 1.16rem; font-weight: 750; }
.cta p { margin: 0 0 16px; color: var(--muted); font-size: .94rem; }

footer.site {
  margin-top: 48px; border-top: 1px solid var(--line);
  padding: 40px 0 44px; color: var(--muted); font-size: .86rem;
  background: linear-gradient(180deg, transparent, rgba(8, 18, 38, .8));
}
.foot-grid { display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 32px; }
.foot-grid h4 { color: #fff; font-size: .84rem; text-transform: uppercase; letter-spacing: 1.2px; margin: 0 0 12px; }
.foot-grid ul { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 7px; }
.foot-grid a { color: var(--muted); }
.foot-grid a:hover { color: var(--accent); }
.foot-brand .logo { font-size: .95rem; margin-bottom: 10px; }
.foot-brand p { margin: 0 0 8px; line-height: 1.65; }
.foot-legal {
  margin-top: 30px; padding-top: 18px; border-top: 1px solid var(--line);
  display: flex; flex-wrap: wrap; gap: 6px 18px; justify-content: space-between; font-size: .8rem;
}

/* faq / breadcrumb / misc */
.faq dt { color: #fff; font-weight: 650; margin-top: 16px; }
.faq dd { margin: 4px 0 0; color: var(--muted); }
.breadcrumb { font-size: .8rem; color: var(--muted); margin-bottom: 20px; }
.breadcrumb a { color: var(--muted); }
.breadcrumb a:hover { color: var(--accent); }
.cat-count { color: var(--muted); font-size: .9rem; margin: 4px 0 0; }

@media (max-width: 860px) {
  .foot-grid { grid-template-columns: 1fr; gap: 24px; }
  .hero { padding: 60px 0 48px; }
  .site-inner { gap: 10px; }
  .langs { max-width: none; order: 3; }
  nav.main { order: 2; margin-inline-start: 0; width: 100%; }
  .foot-legal { flex-direction: column; }
}

/* Inline contextual CTA (link policy 2026-10-24): max 1 per procurement article,
   subtle, blends into body copy — no box/banner styling to avoid link-scheme signals */
.inline-cta {
  margin: 18px 0;
  padding: 10px 16px;
  border-inline-start: 3px solid var(--accent-dim, rgba(56, 189, 248, .45));
  background: rgba(56, 189, 248, .06);
  border-radius: 0 10px 10px 0;
  font-size: .92rem;
}
.inline-cta a { color: #7dd3fc; text-decoration: none; border-bottom: 1px dotted rgba(125, 211, 252, .5); }
.inline-cta a:hover { border-bottom-style: solid; }
[dir="rtl"] .inline-cta { border-radius: 10px 0 0 10px; }