/* =================================================================
   SRRRS — Palette B (warm paper). Tokens are starting values.
   One accent + warm neutrals + generous whitespace. Navy is used
   only as accent / hero highlight — never as a page background.
   ================================================================= */
:root{
  --paper:#F4F1EA;
  --surface:#FFFFFF;
  --surface-soft:#FBF9F4;    /* warm near-white — gentle alternation, no warm/cool clash */
  --ink:#16181C;
  --muted:#6B6B63;
  --line:#E4E0D6;
  --accent:#1E3A6E;          /* navy — links / keywords */
  --accent-strong:#2547D0;   /* CTA / hover */

  --ink-soft:#3c3f46;
  --dark:#16181C;            /* hero / stats dark section */
  --maxw:1120px;
  --radius:12px;
  --font:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,
         "PingFang SC","Microsoft YaHei","Noto Sans CJK SC",sans-serif;
}

*,*::before,*::after{box-sizing:border-box;}
html{scroll-behavior:smooth;}
body{
  margin:0;
  font-family:var(--font);
  background:var(--paper);
  color:var(--ink);
  line-height:1.65;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
h1,h2,h3,p{margin:0;}
a{color:var(--accent);text-decoration:none;}
a:hover{color:var(--accent-strong);}

.container{width:100%;max-width:var(--maxw);margin:0 auto;padding:0 24px;}
.narrow{max-width:760px;}

/* ---------- Buttons ---------- */
.btn{
  display:inline-block;padding:11px 20px;border-radius:8px;
  font-weight:600;font-size:.95rem;line-height:1;
  border:1px solid transparent;cursor:pointer;
  transition:background .15s ease,color .15s ease,border-color .15s ease,transform .05s ease;
}
.btn:active{transform:translateY(1px);}
.btn-cta{background:var(--accent-strong);color:#fff;border-color:var(--accent-strong);}
.btn-cta:hover{background:#1b39b8;color:#fff;}
.btn-ghost{background:transparent;color:#fff;border-color:rgba(255,255,255,.35);}
.btn-ghost:hover{border-color:#fff;color:#fff;}

/* ---------- Header ---------- */
.site-header{
  position:sticky;top:0;z-index:50;
  background:var(--paper);                 /* fully opaque at the top — hides the blur, reads as solid over the dark hero */
  border-bottom:1px solid var(--line);
  /* Keep backdrop-filter ALWAYS on so its compositing layer is never created/destroyed
     mid-scroll — that teardown is what flashed the bar on large screens. Only the
     (interpolatable) background-color changes between states, so the switch stays smooth. */
  backdrop-filter:saturate(180%) blur(10px);
  -webkit-backdrop-filter:saturate(180%) blur(10px);
  transition:background-color .25s ease, box-shadow .25s ease;
}
.site-header.scrolled{                     /* frosted only once light content scrolls under it */
  background:rgba(244,241,234,.82);        /* now translucent — the always-on blur shows through */
  box-shadow:0 1px 0 rgba(22,24,28,.04);
}
.header-inner{display:flex;align-items:center;gap:24px;height:64px;}
.brand{font-weight:700;letter-spacing:.06em;font-size:1.05rem;color:var(--ink);user-select:none;}
.header-menu{display:flex;align-items:center;gap:22px;margin-left:auto;}
.nav{display:flex;align-items:center;gap:2px;}
.nav-link{
  color:var(--ink);font-size:.92rem;font-weight:500;
  padding:8px 13px;border-radius:7px;
  transition:background .15s ease,color .15s ease;
}
.nav-link:hover{background:rgba(30,58,110,.08);color:var(--accent);}
.nav-divider{width:1px;height:20px;background:#cdc6b6;margin:0 10px;}
.header-actions{display:flex;align-items:center;gap:12px;}
.hamburger{display:none;}

/* ---------- Hero (dark, for contrast) ---------- */
.hero{
  background:var(--dark);color:#EDEBE4;
  padding:108px 0 96px;position:relative;overflow:hidden;
}
.hero::after{ /* navy used strictly as an accent glow */
  content:"";position:absolute;top:-30%;right:-8%;
  width:520px;height:520px;border-radius:50%;
  background:radial-gradient(circle,rgba(37,71,208,.22),transparent 70%);
  pointer-events:none;
}
.hero-inner{position:relative;z-index:1;max-width:820px;}
.hero-brand{
  font-size:clamp(3.6rem,10vw,6.5rem);font-weight:800;letter-spacing:-.03em;line-height:.98;
  color:#F2F0EA;
}
.hero-name{font-size:clamp(1.15rem,2.9vw,1.6rem);color:#b9b6ad;margin-top:18px;font-weight:500;}
.hero-lede{margin-top:26px;font-size:1.12rem;color:#d7d4cb;max-width:680px;}
.hero-cta{display:flex;gap:14px;margin-top:34px;flex-wrap:wrap;}

/* ---------- Kicker / section headings ---------- */
.kicker{
  text-transform:uppercase;letter-spacing:.16em;font-size:.74rem;font-weight:700;
  color:var(--accent);margin-bottom:16px;
}
.kicker-on-dark{color:var(--accent-strong);}
.section{padding:84px 0;}
.section-alt{background:var(--surface-soft);border-top:1px solid var(--line);border-bottom:1px solid var(--line);}
.section-title{font-size:clamp(1.6rem,3.4vw,2.2rem);font-weight:700;letter-spacing:-.01em;line-height:1.2;margin-bottom:22px;}
.lede{font-size:1.1rem;color:var(--ink-soft);max-width:760px;margin-bottom:16px;}
/* navy "stitching" — key terms threaded through the copy */
.term{color:var(--accent);font-weight:600;}
#architecture .section-title{font-size:clamp(1.4rem,2.6vw,1.85rem);}

/* ---------- Architecture diagram + layers ---------- */
.arch-diagram{display:block;width:100%;max-width:640px;height:auto;margin:34px auto 12px;}
.layer-notes{display:grid;grid-template-columns:repeat(3,1fr);gap:30px 34px;margin-top:30px;}
.layer-note{border-top:2px solid var(--line);padding-top:16px;}
.layer-note-tag{font-size:.92rem;font-weight:700;color:var(--accent);margin-bottom:8px;}
.layer-note p:not(.layer-note-tag){color:var(--ink-soft);font-size:.96rem;line-height:1.55;}

/* ---------- Service cards ---------- */
.card-grid{margin-top:34px;display:grid;gap:18px;grid-template-columns:repeat(auto-fit,minmax(300px,1fr));}
.card{
  background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);
  padding:26px 24px;box-shadow:0 1px 2px rgba(22,24,28,.04);
  transition:border-color .15s ease,transform .15s ease,box-shadow .15s ease;
}
.card:hover{border-color:#b9c4dd;transform:translateY(-2px);box-shadow:0 14px 34px -20px rgba(30,58,110,.3);}
.card-tag{font-size:.72rem;font-weight:700;letter-spacing:.08em;text-transform:uppercase;color:var(--accent);margin-bottom:10px;}
.card-title{font-size:1.18rem;font-weight:600;margin-bottom:12px;}
.card-body{color:var(--ink-soft);font-size:.97rem;}

/* ---------- Value grid ---------- */
.value-grid{margin-top:34px;display:grid;gap:30px 40px;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));}
.value-item{border-left:2px solid var(--accent);padding-left:20px;}
.value-title{font-size:1.12rem;font-weight:600;margin-bottom:10px;}
.value-item p{color:var(--ink-soft);}

/* ---------- Quickstart + terminal ---------- */
.quickstart-grid{display:grid;grid-template-columns:0.85fr 1.15fr;gap:48px;align-items:center;}
.quickstart-intro .lede{margin-bottom:26px;}
.terminal{
  border-radius:14px;overflow:hidden;background:#15171c;border:1px solid #2a2e36;
  box-shadow:0 30px 70px -30px rgba(22,24,28,.55);
}
.terminal-bar{display:flex;align-items:center;gap:8px;padding:12px 16px;background:#1d2128;border-bottom:1px solid #2a2e36;}
.t-dot{width:11px;height:11px;border-radius:50%;}
.t-dot:nth-child(1){background:#ff5f57;}
.t-dot:nth-child(2){background:#febc2e;}
.t-dot:nth-child(3){background:#28c840;}
.terminal-title{margin-left:8px;color:#7e828b;font-size:.8rem;letter-spacing:.02em;}
.terminal-body{
  padding:22px 22px 24px;overflow-x:auto;
  font-family:"SFMono-Regular",ui-monospace,"JetBrains Mono","Fira Code",Consolas,Menlo,monospace;
  font-size:.9rem;line-height:1.85;color:#cfd2d6;
}
.t-line{white-space:pre;}
.t-spacer{line-height:.7;}
.t-prompt{color:var(--accent-strong);font-weight:700;}
.t-cmd{color:#fff;font-weight:600;}
.t-flag{color:#8b8f98;}
.t-out{color:#9aa0aa;}
.t-ok,.t-up{color:#4ec9a5;font-weight:700;}
.t-link{color:#7d97ff;}
.t-dim{color:#6f7480;}

/* ---------- Stats band (dark) ---------- */
.stats-band{
  background:linear-gradient(180deg,#191b20 0%,#131419 100%);color:#EDEBE4;
  padding:84px 0;position:relative;overflow:hidden;
}
.stats-band::before{ /* same navy depth as hero, so the two dark bands read as a pair */
  content:"";position:absolute;left:50%;top:-55%;width:760px;height:760px;
  transform:translateX(-50%);
  background:radial-gradient(circle,rgba(37,71,208,.16),transparent 70%);
  pointer-events:none;
}
.stats-head{position:relative;z-index:1;margin-bottom:52px;max-width:620px;}
.stats-title{font-size:clamp(1.5rem,3vw,2rem);font-weight:700;color:#fff;letter-spacing:-.01em;margin-top:8px;}
.stats-inner{display:grid;grid-template-columns:repeat(6,1fr);position:relative;z-index:1;}
.stat{display:flex;flex-direction:column;padding:2px 28px;border-left:1px solid rgba(255,255,255,.1);}
.stat:first-child{padding-left:0;border-left:none;}
.stat-num{
  font-size:clamp(3.4rem,4.8vw,4.75rem);font-weight:800;line-height:.92;color:#fff;
  font-variant-numeric:tabular-nums;letter-spacing:-.03em;
}
.stat-label{margin-top:18px;font-size:.85rem;color:#b4b1a8;line-height:1.45;}

/* ---------- FAQ ---------- */
.faq{margin-top:30px;}
.faq-item{border-bottom:1px solid var(--line);}
.faq-item summary{
  cursor:pointer;list-style:none;padding:18px 0;
  font-size:1.05rem;font-weight:600;color:var(--ink);
  display:flex;justify-content:space-between;align-items:center;gap:16px;
}
.faq-item summary::-webkit-details-marker{display:none;}
.faq-item summary::after{content:"+";color:var(--accent);font-weight:700;font-size:1.3rem;line-height:1;}
.faq-item[open] summary::after{content:"\2013";}
.faq-item p{padding:0 0 20px;color:var(--ink-soft);max-width:720px;}

/* ---------- Footer ---------- */
.site-footer{background:var(--paper);border-top:1px solid var(--line);padding:64px 0 0;}
.footer-grid{display:grid;gap:36px;grid-template-columns:1.5fr repeat(4,1fr);}
.footer-brand .brand{font-size:1.1rem;}
.footer-tagline{color:var(--muted);font-size:.9rem;margin-top:12px;max-width:240px;}
.footer-title{font-size:.76rem;text-transform:uppercase;letter-spacing:.1em;color:var(--muted);font-weight:700;margin-bottom:16px;}
.footer-list{list-style:none;margin:0;padding:0;display:grid;gap:11px;}
.footer-link{
  color:var(--ink-soft);font-size:.92rem;
  background:none;border:none;padding:0;font-family:inherit;cursor:pointer;text-align:left;
}
.footer-link:hover{color:var(--accent);}
.footer-static{color:var(--ink-soft);font-size:.92rem;cursor:default;} /* products: non-clickable, same tone as links */
.footer-bottom{
  border-top:1px solid var(--line);margin-top:56px;padding-top:22px;padding-bottom:30px;
  display:flex;align-items:center;justify-content:space-between;gap:14px;flex-wrap:wrap;
}
.footer-bottom p{color:var(--muted);font-size:.85rem;}
.footer-lang{display:flex;align-items:center;gap:9px;flex-wrap:wrap;}
.footer-lang-link{color:var(--muted);font-size:.85rem;}
.footer-lang-link:hover{color:var(--accent);}
.footer-lang-link.is-active{color:var(--ink);font-weight:600;}
.footer-lang-sep{color:#cdc6b6;font-size:.85rem;}

/* ---------- Back-to-top floating arrow ---------- */
.to-top{
  position:fixed;right:26px;bottom:26px;z-index:40;
  width:46px;height:46px;border-radius:50%;
  background:var(--accent);color:#fff;border:none;cursor:pointer;
  font-size:1.2rem;line-height:1;
  display:flex;align-items:center;justify-content:center;
  box-shadow:0 8px 24px -8px rgba(22,24,28,.5);
  opacity:0;visibility:hidden;transform:translateY(8px);
  transition:opacity .2s ease,transform .2s ease,visibility .2s ease,background .15s ease;
}
.to-top.show{opacity:1;visibility:visible;transform:translateY(0);}
.to-top:hover{background:var(--accent-strong);}

/* ---------- Modal (pure front-end) ---------- */
.modal{position:fixed;inset:0;z-index:60;display:flex;align-items:center;justify-content:center;padding:24px;}
.modal[hidden]{display:none;}
.modal-backdrop{position:absolute;inset:0;background:rgba(22,24,28,.55);}
.modal-card{
  position:relative;background:var(--surface);border-radius:14px;
  padding:34px 30px 28px;max-width:420px;width:100%;text-align:center;
  box-shadow:0 30px 80px -20px rgba(22,24,28,.55);
}
.modal-text{font-size:1.05rem;color:var(--ink);margin-bottom:24px;line-height:1.55;}
.modal-close{min-width:120px;}

/* ---------- Responsive ---------- */
@media (max-width:920px){
  .stats-inner{grid-template-columns:repeat(3,1fr);row-gap:40px;column-gap:20px;}
  .stat{border-left:none;padding:0;}
  .quickstart-grid{grid-template-columns:1fr;gap:32px;}
  .footer-grid{grid-template-columns:1fr 1fr;}
}
@media (max-width:760px){
  .hamburger{
    display:flex;flex-direction:column;justify-content:center;gap:5px;
    width:42px;height:42px;margin-left:auto;background:none;border:none;cursor:pointer;padding:8px;
  }
  .hamburger span{display:block;height:2px;width:100%;background:var(--ink);border-radius:2px;
    transition:transform .2s ease,opacity .2s ease;}
  .site-header.menu-open .hamburger span:nth-child(1){transform:translateY(7px) rotate(45deg);}
  .site-header.menu-open .hamburger span:nth-child(2){opacity:0;}
  .site-header.menu-open .hamburger span:nth-child(3){transform:translateY(-7px) rotate(-45deg);}

  .header-menu{
    position:absolute;left:0;right:0;top:64px;display:none;
    flex-direction:column;align-items:stretch;gap:0;margin-left:0;
    background:var(--surface);border-bottom:1px solid var(--line);
    padding:12px 24px 20px;
    box-shadow:0 16px 30px -20px rgba(22,24,28,.5);
  }
  .site-header.menu-open .header-menu{display:flex;}
  .nav{flex-direction:column;align-items:stretch;gap:2px;}
  .nav-link{padding:12px 8px;font-size:1rem;}
  .nav-divider{display:none;}
  .header-actions{flex-direction:column;align-items:stretch;gap:12px;margin-top:12px;}
  .btn-cta{text-align:center;}

  .section{padding:60px 0;}
  .hero{padding:80px 0 64px;}
  .stats-inner{grid-template-columns:repeat(2,1fr);row-gap:36px;}
  .footer-grid{grid-template-columns:1fr 1fr;gap:28px;}
  .layer-notes{grid-template-columns:1fr;gap:0;}
  .layer-note{border-top:1px solid var(--line);padding:20px 0;}
}
@media (max-width:460px){
  .footer-grid{grid-template-columns:1fr 1fr;}
  .to-top{right:18px;bottom:18px;}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto;}
  *{transition:none !important;}
}