:root{
  --bg:#f5f8fb;
  --paper:#ffffff;
  --ink:#182631;
  --muted:#61717e;
  --line:#dbe5ec;
  --blue:#0b5f88;
  --blue2:#0d789c;
  --soft:#eaf4f8;
  --accent:#9b6a16;
  --max:1180px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;
  background:var(--bg);
  color:var(--ink);
  font:15px/1.62 Inter,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",Arial,sans-serif;
}
a{color:var(--blue);text-decoration:none}
a:hover{text-decoration:underline}
.wrap{width:min(var(--max),calc(100% - 32px));margin:0 auto}
.topbar{
  background:#0d2635;color:#d9e7ef;font-size:13px
}
.topbar .wrap{
  min-height:38px;display:flex;align-items:center;justify-content:space-between;gap:16px
}
.topbar a{color:#e9f4f9}
.lang{display:flex;gap:6px}
.lang a{
  border:1px solid rgba(255,255,255,.22);
  border-radius:4px;padding:2px 7px
}
header{
  background:linear-gradient(135deg,#075274 0%,#0a698c 50%,#0d789c 100%);
  color:white;
  border-bottom:5px solid #d9b66f
}
.head{
  padding:24px 0 18px;
  display:flex;align-items:flex-end;justify-content:space-between;gap:30px
}
.brand small{
  display:block;text-transform:uppercase;letter-spacing:.14em;font-weight:700;
  color:#c9e7f2;font-size:12px
}
.brand h1{
  margin:4px 0 2px;
  font:600 34px/1.15 Georgia,"Times New Roman",serif
}
.brand p{margin:0;color:#e2f0f5}
.nav{
  display:flex;gap:6px;flex-wrap:wrap;justify-content:flex-end
}
.nav a{
  color:white;border:1px solid rgba(255,255,255,.32);
  padding:7px 10px;border-radius:5px;font-weight:600;font-size:13px
}
.hero{
  background:
    radial-gradient(circle at 85% 30%,rgba(13,120,156,.18),transparent 30%),
    linear-gradient(#fff,#f7fbfd);
  border-bottom:1px solid var(--line)
}
.hero .wrap{
  padding:66px 0 58px;
  display:grid;grid-template-columns:minmax(0,1.65fr) minmax(280px,.75fr);gap:55px;align-items:center
}
.kicker{
  text-transform:uppercase;letter-spacing:.14em;color:var(--blue2);
  font-weight:800;font-size:12px
}
.hero h2{
  margin:8px 0 16px;
  font:600 43px/1.12 Georgia,"Times New Roman",serif;
  color:#12384d
}
.hero p{font-size:18px;color:#4a5f6d;max-width:760px}
.actions{display:flex;gap:10px;flex-wrap:wrap;margin-top:24px}
.btn{
  display:inline-block;border-radius:5px;padding:10px 16px;font-weight:700;
  border:1px solid var(--blue)
}
.btn.primary{background:var(--blue);color:white}
.btn.secondary{background:white}
.formula{
  border:1px solid var(--line);
  background:white;border-radius:10px;padding:28px;
  box-shadow:0 12px 30px rgba(24,51,70,.08);
  text-align:center
}
.formula .eq{
  font:italic 25px/1.65 Georgia,"Times New Roman",serif;color:#234f66
}
.formula .caption{color:var(--muted);font-size:13px;margin-top:8px}
section{padding:54px 0}
section.alt{background:white;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.section-title{display:flex;align-items:end;justify-content:space-between;gap:20px;margin-bottom:24px}
.section-title h2{margin:0;font:600 28px/1.2 Georgia,"Times New Roman",serif;color:#163f54}
.section-title p{margin:0;color:var(--muted)}
.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}
.card{
  background:var(--paper);border:1px solid var(--line);border-radius:8px;padding:22px;
  box-shadow:0 4px 14px rgba(35,65,84,.04)
}
.alt .card{background:#fbfdfe}
.card h3{margin:0 0 8px;color:#174b65;font-size:18px}
.card p{margin:0 0 14px;color:#5b6c78}
.card .more{font-weight:700}
.archive-card{border-top:4px solid var(--blue2)}
.current-card{border-top:4px solid #3c7a57}
.legacy-card{border-top:4px solid var(--accent)}
.split{display:grid;grid-template-columns:1fr 1fr;gap:24px}
.note{
  padding:22px;border:1px solid var(--line);border-left:5px solid var(--blue2);
  background:#f7fbfd;border-radius:5px
}
.timeline{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin-top:18px}
.milestone{padding:16px;border-top:2px solid var(--line)}
.milestone strong{display:block;color:#14465f;font-size:18px}
footer{background:#112b3a;color:#c9d7df;padding:34px 0}
footer a{color:#e5f1f6}
.footer-grid{display:grid;grid-template-columns:1.4fr 1fr 1fr;gap:30px}
.footer-grid h3{color:white;margin-top:0;font-size:15px}
.footer-grid p{margin:5px 0}
.small{font-size:12px;color:#8295a2}
@media(max-width:900px){
  .head,.topbar .wrap{align-items:flex-start}
  .head{display:block}.nav{justify-content:flex-start;margin-top:18px}
  .hero .wrap,.grid,.split,.timeline,.footer-grid{grid-template-columns:1fr}
  .hero .wrap{gap:25px;padding:44px 0}
  .hero h2{font-size:34px}.formula{display:none}
}
@media(max-width:540px){
  .wrap{width:min(100% - 20px,var(--max))}
  .topbar .wrap{display:block;padding:7px 0}
  .lang{margin-top:5px}
  .brand h1{font-size:27px}
  .hero h2{font-size:30px}
}


/* Navigation width refinement for long Russian labels */
@media(max-width:1200px){
  .head{display:block}
  .nav{justify-content:flex-start;margin-top:18px}
}


.page-hero{padding:46px 0 34px;background:linear-gradient(#fff,#f6fafc);border-bottom:1px solid var(--line)}
.page-hero h2{margin:7px 0 10px;font:600 38px/1.15 Georgia,"Times New Roman",serif;color:#143f55}
.page-hero p{max-width:820px;font-size:17px;color:#536875}
.topic-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:18px}
.topic{background:white;border:1px solid var(--line);border-radius:8px;padding:22px}
.topic h3{margin:0 0 7px;color:#174b65}
.link-list{display:grid;gap:10px}
.link-row{padding:15px 0;border-bottom:1px solid var(--line)}
.link-row:last-child{border-bottom:0}
.link-row strong{display:block;color:#173f55;margin-bottom:3px}
.breadcrumb{font-size:13px;color:var(--muted);margin-bottom:12px}
@media(max-width:760px){.topic-grid{grid-template-columns:1fr}}