:root{--bg:#0C1219;--bg2:#121A24;--bg3:#182230;--line:#243041;--text:#E8EEF4;--muted:#8B9AAB;--accent:#5B9FD4;--accent-dim:rgba(91,159,212,.14);--warn:#C9A35A;--ok:#6BB89A;--danger:#C97A6E}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--text);font:16px/1.7 Inter,system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;-webkit-font-smoothing:antialiased}
a{color:var(--accent)}
.wrap{max-width:760px;margin:0 auto;padding:0 20px}
nav{position:sticky;top:0;z-index:20;background:rgba(12,18,25,.9);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
nav .wrap{max-width:1040px;display:flex;align-items:center;justify-content:space-between;height:60px}
.logo{display:flex;gap:10px;align-items:center;white-space:nowrap;font-weight:700;text-decoration:none;font-size:17px;letter-spacing:-.02em;color:var(--text)}
.logo i{width:28px;height:28px;border-radius:8px;background:var(--accent-dim);border:1px solid rgba(91,159,212,.35);display:grid;place-items:center;font-style:normal;font-weight:800;color:var(--accent);font-size:14px}
.navlinks{display:flex;align-items:center;white-space:nowrap}
.navlinks a{color:var(--muted);text-decoration:none;margin-left:22px;font-size:14px}
.navlinks a:hover,.navlinks a.on{color:var(--text)}
.btn{display:inline-block;background:var(--accent);color:#0A1016;font-weight:700;padding:13px 22px;border-radius:10px;text-decoration:none;font-size:15px;border:0;cursor:pointer}
.btn:hover{background:#6AABDE}
.btn.sm{padding:8px 14px;font-size:13px}
.navlinks a.btn{color:#0A1016}
.btn.ghost{background:transparent;color:var(--text);border:1px solid var(--line)}
main{padding:44px 0 64px}
.crumbs{font-size:13px;color:var(--muted);margin-bottom:14px}.crumbs a{color:var(--muted);text-decoration:none}.crumbs a:hover{color:var(--text)}
.eyebrow{color:var(--accent);font-weight:600;font-size:12px;text-transform:uppercase;letter-spacing:.14em;margin-bottom:10px}
h1{font-size:clamp(30px,5vw,44px);letter-spacing:-.03em;margin:0 0 14px;font-weight:800;line-height:1.12}
h2{font-size:clamp(21px,3vw,26px);margin:40px 0 12px;font-weight:750;letter-spacing:-.02em;line-height:1.25}
h3{font-size:17px;margin:24px 0 8px;font-weight:650}
p,li{color:#C3CDD8}
.lead{font-size:18px;color:var(--muted)}
strong,b{color:var(--text)}
ul,ol{padding-left:22px}li{margin:6px 0}
code{background:var(--bg3);border:1px solid var(--line);border-radius:6px;padding:1px 6px;font-size:.92em}
.panel{background:var(--bg2);border:1px solid var(--line);border-radius:14px;padding:20px;margin-top:20px}
.example{background:var(--bg2);border:1px solid var(--line);border-left:3px solid var(--warn);border-radius:12px;padding:16px 18px;margin:18px 0}
.example .tag,.tag{display:inline-block;font-size:10px;font-weight:700;padding:2px 8px;border-radius:999px;background:rgba(201,163,90,.14);color:var(--warn);letter-spacing:.05em;text-transform:uppercase;vertical-align:middle}
.example p:first-child{margin-top:0}.example p:last-child{margin-bottom:0}
.math{font-family:ui-monospace,SFMono-Regular,Menlo,monospace;font-size:14px;background:var(--bg3);border:1px solid var(--line);border-radius:10px;padding:12px 14px;overflow-x:auto;white-space:pre;color:var(--text);line-height:1.6}
.table-wrap{overflow-x:auto;border:1px solid var(--line);border-radius:12px;margin:16px 0}
table{width:100%;border-collapse:collapse;font-size:14px}
th,td{padding:10px 14px;text-align:left;border-bottom:1px solid var(--line)}
th{background:var(--bg3);color:var(--muted);font-weight:600;font-size:12px;text-transform:uppercase;letter-spacing:.06em}
td{background:var(--bg2)}tr:last-child td{border-bottom:none}
td.ok{color:var(--ok);font-weight:650}td.bad{color:var(--danger);font-weight:650}
/* calculator */
form.calc{display:grid;grid-template-columns:1fr 1fr;gap:12px 14px}
form.calc .full{grid-column:1/-1}
form.calc label{display:flex;flex-direction:column;font-size:13px;color:var(--muted);gap:5px;font-weight:600}
form.calc input[type=number]{background:var(--bg3);border:1px solid var(--line);color:var(--text);border-radius:10px;padding:12px;font-size:16px;font-family:inherit;width:100%}
form.calc input:focus{outline:2px solid rgba(91,159,212,.5);border-color:var(--accent)}
.seg{display:flex;gap:8px;flex-wrap:wrap}
.seg label{flex:1;flex-direction:row!important;align-items:center;justify-content:center;gap:8px;background:var(--bg3);border:1px solid var(--line);border-radius:10px;padding:10px;color:var(--text)!important;cursor:pointer;min-width:140px}
.seg label:has(input:checked){border-color:var(--accent);background:var(--accent-dim)}
.hint{font-weight:400;font-size:12px;color:#6B7A8A}
.stats{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-top:18px}
.stat{background:var(--bg3);border:1px solid var(--line);border-radius:12px;padding:12px 14px}
.stat .k{font-size:12px;color:var(--muted);text-transform:uppercase;letter-spacing:.06em}
.stat .v{font-size:22px;font-weight:800;letter-spacing:-.02em}
.stat.ok .v{color:var(--ok)}.stat.warn .v{color:var(--warn)}
.plain{background:var(--accent-dim);border:1px solid rgba(91,159,212,.3);border-radius:12px;padding:14px 16px;color:var(--text);margin:14px 0 0}
.fine{font-size:12px;color:#6B7A8A;margin:10px 0 0}
.err{color:var(--danger);font-weight:600;margin:16px 0 0}
.pltable table{font-size:14px}
/* cta */
.cta{margin:36px 0;padding:24px 22px;border-radius:16px;background:linear-gradient(135deg,rgba(91,159,212,.16),rgba(107,184,154,.08));border:1px solid rgba(91,159,212,.4)}
.cta h2{margin:0 0 8px;font-size:22px}
.cta p{margin:0 0 16px;color:var(--muted)}
.cta .row{display:flex;flex-wrap:wrap;gap:10px;align-items:center}
.cta .small{font-size:13px;margin:14px 0 0}
.cta .small a{color:var(--accent)}
/* faq */
details{background:var(--bg2);border:1px solid var(--line);border-radius:12px;padding:14px 16px;margin-top:10px}
summary{cursor:pointer;font-weight:600;list-style:none;display:flex;justify-content:space-between;gap:12px}
summary::-webkit-details-marker{display:none}
summary:after{content:"+";color:var(--accent);font-size:20px;line-height:1}
details[open] summary:after{content:"–"}
details p{margin:10px 0 0}
.grid{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-top:20px}
.tile{display:block;background:var(--bg2);border:1px solid var(--line);border-radius:14px;padding:18px;text-decoration:none;color:var(--text);transition:border-color .15s}
.tile:hover{border-color:var(--accent)}
.tile h3{margin:0 0 6px}.tile p{margin:0;color:var(--muted);font-size:14px}
.related{display:flex;gap:10px;flex-wrap:wrap;margin-top:10px}
.related a{background:var(--bg2);border:1px solid var(--line);border-radius:999px;padding:6px 12px;text-decoration:none;font-size:14px;color:var(--text)}
.edu{font-size:13px;color:var(--muted);border:1px solid rgba(201,163,90,.35);background:rgba(201,163,90,.07);border-radius:12px;padding:12px 14px;margin:24px 0}
.edu b{color:var(--warn)}
footer{padding:36px 0 48px;color:var(--muted);font-size:13px;border-top:1px solid var(--line)}
footer .wrap{max-width:1040px;display:flex;flex-direction:column;gap:16px}
.footer-top{display:flex;justify-content:space-between;flex-wrap:wrap;gap:12px;align-items:center}
.footer-links a{color:var(--muted);text-decoration:none;margin-left:16px}
.footer-links a:hover{color:var(--text)}.footer-links a:first-child{margin-left:0}
.disclaimer{font-size:12px;line-height:1.55;color:#6B7A8A;margin:0}
@media(max-width:640px){.navlinks a:not(.btn):not(.keep){display:none}.navlinks a{margin-left:12px;font-size:13px}.logo{font-size:15px;gap:8px}.btn.sm{padding:7px 10px;font-size:12px}form.calc,.grid{grid-template-columns:1fr}main{padding:28px 0 52px}.stat .v{font-size:19px}}