:root{
  --navy:#14213d;--navy-2:#1f3160;--ink:#1b1f2a;--muted:#5b6475;--line:#e3e7ef;
  --bg:#ffffff;--bg-soft:#f5f7fb;--accent:#0f766e;--accent-2:#0d9488;--accent-soft:#e6f4f2;
  --gold:#d97706;--good:#15803d;--good-soft:#e8f6ec;--bad:#b91c1c;--bad-soft:#fdecec;
  --radius:14px;--shadow:0 6px 24px rgba(20,33,61,.08);
  --font:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:var(--font);color:var(--ink);background:var(--bg);line-height:1.65;font-size:17px;-webkit-font-smoothing:antialiased}
img{max-width:100%;height:auto}
a{color:var(--accent);text-underline-offset:3px}
a:hover{color:var(--navy)}
h1,h2,h3{line-height:1.2;color:var(--navy);letter-spacing:-.01em}
h1{font-size:clamp(2rem,4.6vw,3rem);margin:.2em 0 .4em}
h2{font-size:clamp(1.5rem,3vw,2rem);margin:0 0 .6em}
h3{font-size:1.2rem;margin:1.4em 0 .4em}
.container{width:100%;max-width:1120px;margin:0 auto;padding:0 20px}
.narrow{max-width:820px}
.skip{position:absolute;left:-999px}
.skip:focus{left:12px;top:12px;background:#fff;padding:8px 12px;z-index:99}

/* Header */
.site-header{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.96);backdrop-filter:blur(6px);border-bottom:1px solid var(--line)}
.nav{display:flex;align-items:center;justify-content:space-between;gap:16px;min-height:66px}
.logo{font-weight:800;font-size:1.12rem;color:var(--navy);text-decoration:none;letter-spacing:-.02em;white-space:nowrap}
.logo span{color:var(--accent)}
.logo b{color:var(--gold)}
.menu{display:flex;gap:4px;list-style:none;margin:0;padding:0}
.menu a{display:block;padding:8px 12px;border-radius:8px;text-decoration:none;color:var(--ink);font-weight:600;font-size:.95rem}
.menu a:hover,.menu a[aria-current="page"]{background:var(--accent-soft);color:var(--accent)}
.menu-toggle{display:none;background:none;border:1px solid var(--line);border-radius:8px;padding:8px 10px;font-size:1rem;cursor:pointer}
@media (max-width:860px){
  .menu-toggle{display:block}
  .menu{display:none;position:absolute;left:0;right:0;top:66px;background:#fff;flex-direction:column;padding:10px 20px 18px;border-bottom:1px solid var(--line);box-shadow:var(--shadow)}
  .menu.open{display:flex}
}

/* Hero */
.hero{background:linear-gradient(180deg,var(--bg-soft),#fff);padding:40px 0 24px}
.hero-grid{display:grid;grid-template-columns:1fr;gap:28px}
.eyebrow{display:inline-block;background:var(--accent-soft);color:var(--accent);font-weight:700;font-size:.82rem;padding:5px 12px;border-radius:999px;letter-spacing:.02em}
.lead{font-size:1.15rem;color:var(--muted);max-width:760px}
.updated{font-size:.9rem;color:var(--muted)}
.facts{display:grid;grid-template-columns:repeat(4,1fr);gap:12px;margin:22px 0 0}
.fact{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:14px 16px}
.fact strong{display:block;font-size:1.6rem;color:var(--navy);line-height:1.1}
.fact span{font-size:.88rem;color:var(--muted)}
@media (max-width:640px){.facts{grid-template-columns:repeat(2,1fr)}}

/* Sections */
section.block{padding:52px 0}
section.alt{background:var(--bg-soft)}
.grid-3{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}
.grid-2{display:grid;grid-template-columns:repeat(2,1fr);gap:18px}
@media (max-width:860px){.grid-3,.grid-2{grid-template-columns:1fr}}
.card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:22px;box-shadow:var(--shadow)}
.card h3{margin-top:0}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;background:var(--accent);color:#fff;border:0;border-radius:10px;padding:12px 20px;font-weight:700;font-size:1rem;text-decoration:none;cursor:pointer;font-family:inherit}
.btn:hover{background:var(--navy);color:#fff}
.btn.secondary{background:#fff;color:var(--navy);border:2px solid var(--navy)}
.btn.secondary:hover{background:var(--navy);color:#fff}
.btn:disabled{opacity:.45;cursor:not-allowed}
table{width:100%;border-collapse:collapse;background:#fff;border-radius:var(--radius);overflow:hidden;border:1px solid var(--line);font-size:.97rem}
th,td{padding:12px 14px;text-align:left;border-bottom:1px solid var(--line);vertical-align:top}
th{background:var(--navy);color:#fff;font-weight:700}
tr:last-child td{border-bottom:0}
.table-wrap{overflow-x:auto}
.note{background:#fff8eb;border-left:4px solid var(--gold);padding:14px 16px;border-radius:8px;font-size:.95rem}
.answer-box{background:var(--accent-soft);border-left:4px solid var(--accent);padding:16px 18px;border-radius:8px}
ol.steps,ul.ticks{padding-left:1.2em}
ul.ticks li{margin:.35em 0}
details{background:#fff;border:1px solid var(--line);border-radius:12px;padding:0 18px;margin:10px 0}
details summary{cursor:pointer;font-weight:700;padding:15px 0;color:var(--navy);list-style:none;position:relative;padding-right:28px}
details summary::-webkit-details-marker{display:none}
details summary::after{content:"+";position:absolute;right:0;top:12px;font-size:1.4rem;color:var(--accent)}
details[open] summary::after{content:"–"}
details>div{padding:0 0 16px}
.breadcrumb{font-size:.9rem;color:var(--muted);margin:0;padding:14px 0 0}
.breadcrumb a{color:var(--muted)}

/* Quiz tool */
.tool{background:#fff;border:1px solid var(--line);border-radius:18px;box-shadow:0 12px 40px rgba(20,33,61,.12);overflow:hidden}
.tool-head{background:var(--navy);color:#fff;padding:16px 20px;display:flex;justify-content:space-between;align-items:center;gap:12px;flex-wrap:wrap}
.tool-head h2{color:#fff;font-size:1.15rem;margin:0}
.tool-body{padding:22px}
.modes{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin-bottom:16px}
@media (max-width:640px){.modes{grid-template-columns:1fr}}
.mode{border:2px solid var(--line);border-radius:12px;padding:14px;background:#fff;text-align:left;cursor:pointer;font-family:inherit;font-size:.95rem;color:var(--ink)}
.mode strong{display:block;color:var(--navy);font-size:1.02rem}
.mode[aria-pressed="true"]{border-color:var(--accent);background:var(--accent-soft)}
.chapter-select{width:100%;padding:12px;border-radius:10px;border:1px solid var(--line);font-size:1rem;font-family:inherit;margin:0 0 16px}
.q-meta{display:flex;justify-content:space-between;align-items:center;gap:10px;font-size:.92rem;color:var(--muted);margin-bottom:8px;flex-wrap:wrap}
.timer{font-weight:800;color:#fff;background:var(--accent);padding:4px 10px;border-radius:8px;font-variant-numeric:tabular-nums}
.timer.low{background:var(--bad)}
.progress{height:8px;background:var(--line);border-radius:99px;overflow:hidden;margin-bottom:18px}
.progress i{display:block;height:100%;background:var(--accent);width:0;transition:width .25s}
.q-text{font-size:1.2rem;font-weight:700;color:var(--navy);margin:0 0 16px}
.options{display:grid;gap:10px;margin:0;padding:0;list-style:none}
.opt{width:100%;text-align:left;padding:14px 16px;border:2px solid var(--line);border-radius:12px;background:#fff;font-size:1rem;font-family:inherit;color:var(--ink);cursor:pointer;display:flex;gap:12px;align-items:flex-start}
.opt:hover:not(:disabled){border-color:var(--accent-2)}
.opt .k{flex:0 0 28px;height:28px;border-radius:50%;background:var(--bg-soft);display:inline-flex;align-items:center;justify-content:center;font-weight:800;font-size:.85rem;color:var(--navy)}
.opt.selected{border-color:var(--navy);background:#eef2fb}
.opt.correct{border-color:var(--good);background:var(--good-soft)}
.opt.wrong{border-color:var(--bad);background:var(--bad-soft)}
.opt:disabled{cursor:default}
.feedback{margin-top:14px;padding:14px 16px;border-radius:10px;font-size:.97rem}
.feedback.ok{background:var(--good-soft);border-left:4px solid var(--good)}
.feedback.no{background:var(--bad-soft);border-left:4px solid var(--bad)}
.q-actions{display:flex;justify-content:space-between;gap:10px;margin-top:18px;flex-wrap:wrap}
.dots{display:flex;flex-wrap:wrap;gap:6px;margin-top:16px}
.dot{width:30px;height:30px;border-radius:8px;border:1px solid var(--line);background:#fff;font-size:.78rem;font-weight:700;cursor:pointer;color:var(--muted);font-family:inherit}
.dot.answered{background:var(--navy);color:#fff;border-color:var(--navy)}
.dot.current{outline:3px solid var(--accent-2)}
.result{text-align:center;padding:10px 0 4px}
.score{font-size:3rem;font-weight:900;color:var(--navy);line-height:1}
.badge{display:inline-block;padding:6px 14px;border-radius:999px;font-weight:800;margin:10px 0}
.badge.pass{background:var(--good-soft);color:var(--good)}
.badge.fail{background:var(--bad-soft);color:var(--bad)}
.review{margin-top:22px;text-align:left}
.review-item{border:1px solid var(--line);border-radius:12px;padding:14px 16px;margin:10px 0}
.review-item.r-ok{border-left:5px solid var(--good)}
.review-item.r-no{border-left:5px solid var(--bad)}
.review-item p{margin:.3em 0}
.chap-bars{margin:16px 0 0;text-align:left}
.chap-bar{display:grid;grid-template-columns:1fr 60px;gap:10px;align-items:center;font-size:.9rem;margin:6px 0}
.chap-bar .bar{height:8px;background:var(--line);border-radius:99px;overflow:hidden;grid-column:1/-1}
.chap-bar .bar i{display:block;height:100%;background:var(--accent)}
.history{font-size:.9rem;color:var(--muted);margin-top:10px}
noscript .note{margin:16px}

/* Footer */
.site-footer{background:var(--navy);color:#cfd6e6;padding:46px 0 26px;margin-top:20px;font-size:.95rem}
.site-footer a{color:#fff}
.site-footer h3{color:#fff;font-size:1rem;margin:0 0 10px}
.foot-grid{display:grid;grid-template-columns:2fr 1fr 1fr;gap:26px}
@media (max-width:760px){.foot-grid{grid-template-columns:1fr}}
.site-footer ul{list-style:none;padding:0;margin:0}
.site-footer li{margin:6px 0}
.disclaimer{border-top:1px solid rgba(255,255,255,.15);margin-top:28px;padding-top:18px;font-size:.85rem}