/* TRXAPI shared design system — dark theme, all pages */
:root{
  --bg:#0a0e17;--bg2:#0e1424;--card:rgba(255,255,255,.04);--card-brd:rgba(255,255,255,.08);
  --txt:#eaf0ff;--muted:#9aa7c2;--brand:#2e6cf6;--brand2:#2ee6c8;--danger:#ff5b45;--cyan:#2ee6c8;--green:#28e07a;
  --grad:linear-gradient(135deg,#2e6cf6 0%,#2ee6c8 100%);
  --grad2:linear-gradient(135deg,#2ee6c8 0%,#28a3ff 100%);
  --radius:18px;--maxw:1160px;
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{font-family:"PingFang SC","PingFang TC","Microsoft YaHei","Helvetica Neue",system-ui,-apple-system,Segoe UI,Roboto,sans-serif;
  background:var(--bg);color:var(--txt);line-height:1.65;overflow-x:hidden;-webkit-font-smoothing:antialiased}
a{color:inherit;text-decoration:none}
img{max-width:100%}
.wrap{max-width:var(--maxw);margin:0 auto;padding:0 20px}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:13px 26px;
  border-radius:999px;font-weight:700;font-size:15px;cursor:pointer;border:none;transition:.25s;white-space:nowrap}
.btn-primary{background:var(--grad);color:#fff;box-shadow:0 8px 24px rgba(46,108,246,.35)}
.btn-primary:hover{transform:translateY(-2px);box-shadow:0 12px 30px rgba(46,108,246,.5)}
.btn-ghost{background:var(--card);color:var(--txt);border:1px solid var(--card-brd)}
.btn-ghost:hover{background:rgba(255,255,255,.09)}
.tag{display:inline-flex;align-items:center;gap:8px;padding:6px 14px;border-radius:999px;
  background:rgba(46,230,200,.1);border:1px solid rgba(46,230,200,.25);color:var(--cyan);font-size:13px;font-weight:600}
.sec{padding:84px 0}
.sec-head{text-align:center;max-width:640px;margin:0 auto 52px}
.sec-head h2{font-size:clamp(26px,5vw,40px);font-weight:800;letter-spacing:-.5px;line-height:1.2}
.sec-head p{color:var(--muted);margin-top:14px;font-size:16px}
.grad-txt{background:var(--grad);-webkit-background-clip:text;background-clip:text;color:transparent}
.grad-txt2{background:var(--grad2);-webkit-background-clip:text;background-clip:text;color:transparent}

/* header */
header{position:sticky;top:0;z-index:50;backdrop-filter:blur(8px);background:rgba(10,14,23,.86);
  border-bottom:1px solid transparent;transition:border-color .3s,background .3s}
header.scrolled{border-bottom:1px solid var(--card-brd);background:rgba(10,14,23,.93)}
.nav{display:flex;align-items:center;justify-content:space-between;height:66px}
.logo{display:flex;align-items:center;gap:10px;font-weight:800;font-size:20px}
.logo .mark{width:34px;height:34px;border-radius:10px;background:var(--grad);display:grid;place-items:center;
  font-size:19px;box-shadow:0 4px 14px rgba(46,108,246,.4)}
.nav-links{display:flex;align-items:center;gap:26px}
.nav-links a{color:var(--muted);font-size:15px;font-weight:500;transition:.2s}
.nav-links a:hover{color:var(--txt)}
.nav-links a.act{color:var(--txt);font-weight:700}
.nav-links a.nav-login{color:var(--txt);border:1px solid var(--card-brd);border-radius:999px;padding:7px 16px}
.nav-links a.nav-login:hover{border-color:var(--brand);color:var(--brand)}
.nav-cta{display:flex;align-items:center;gap:12px}
.lang{display:flex;align-items:center;background:var(--card);border:1px solid var(--card-brd);border-radius:999px;padding:3px}
.lang button{background:none;border:0;color:var(--muted);font-size:13px;font-weight:600;padding:6px 12px;
  border-radius:999px;cursor:pointer;transition:.2s;line-height:1}
.lang button.on{background:var(--grad);color:#fff}
.burger{display:none;flex-direction:column;gap:5px;background:none;border:0;cursor:pointer;padding:8px}
.burger span{width:24px;height:2px;background:var(--txt);border-radius:2px;transition:.3s}

/* hero */
.hero{position:relative;padding:70px 0 40px;overflow:hidden}
.hero::before{content:"";position:absolute;top:-200px;left:50%;transform:translateX(-50%);width:900px;height:700px;
  background:radial-gradient(ellipse 60% 55% at 30% 30%,rgba(46,108,246,.26),transparent 75%),
  radial-gradient(ellipse 60% 55% at 70% 60%,rgba(46,230,200,.2),transparent 75%);z-index:0}
.hero .wrap{position:relative;z-index:1;text-align:center}
.hero h1{font-size:clamp(32px,7vw,60px);font-weight:900;letter-spacing:-1px;line-height:1.12;margin:22px 0 18px}
.hero p.sub{color:var(--muted);font-size:clamp(15px,2.4vw,19px);max-width:640px;margin:0 auto 34px}
.hero-cta{display:flex;gap:14px;justify-content:center;flex-wrap:wrap}
.hero-stats{display:grid;grid-template-columns:repeat(4,1fr);gap:16px;margin-top:56px}
.stat{background:var(--card);border:1px solid var(--card-brd);border-radius:var(--radius);padding:22px 14px}
.stat .num{font-size:clamp(22px,4vw,32px);font-weight:800}
.stat .lbl{color:var(--muted);font-size:13px;margin-top:4px}

/* page hero (inner pages) */
.page-hero{position:relative;padding:64px 0 10px;overflow:hidden}
.page-hero::before{content:"";position:absolute;top:-260px;left:50%;transform:translateX(-50%);width:900px;height:600px;
  background:radial-gradient(ellipse 60% 55% at 30% 30%,rgba(46,108,246,.2),transparent 75%),
  radial-gradient(ellipse 60% 55% at 70% 60%,rgba(46,230,200,.15),transparent 75%);z-index:0}
.page-hero .wrap{position:relative;z-index:1;text-align:center}
.page-hero h1{font-size:clamp(28px,5.6vw,46px);font-weight:900;letter-spacing:-.8px;line-height:1.15;margin:18px 0 14px}
.page-hero p.sub{color:var(--muted);font-size:clamp(15px,2.2vw,18px);max-width:640px;margin:0 auto}

/* cards & grids */
.steps{display:grid;grid-template-columns:repeat(3,1fr);gap:20px;counter-reset:s}
.step{background:var(--card);border:1px solid var(--card-brd);border-radius:var(--radius);padding:30px 24px;position:relative}
.step::before{counter-increment:s;content:counter(s);position:absolute;top:-16px;left:24px;width:44px;height:44px;
  border-radius:12px;background:var(--grad);display:grid;place-items:center;font-weight:900;font-size:20px;
  box-shadow:0 6px 16px rgba(46,108,246,.4)}
.step h3{margin:18px 0 8px;font-size:19px}
.step p{color:var(--muted);font-size:14.5px}
.feat-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.feat{background:var(--card);border:1px solid var(--card-brd);border-radius:var(--radius);padding:28px;transition:.25s;display:block}
.feat:hover{transform:translateY(-4px);border-color:rgba(46,230,200,.35);background:rgba(46,230,200,.04)}
.feat .ic{width:52px;height:52px;border-radius:14px;background:rgba(46,108,246,.12);display:grid;place-items:center;
  font-size:26px;margin-bottom:16px}
.feat h3{font-size:18px;margin-bottom:8px}
.feat p{color:var(--muted);font-size:14.5px}
.feat .go{display:inline-block;margin-top:14px;color:var(--cyan);font-weight:700;font-size:13.5px}
.price-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:22px}
.price{background:var(--card);border:1px solid var(--card-brd);border-radius:22px;padding:32px 28px;position:relative;transition:.25s}
.price:hover{transform:translateY(-4px)}
.price.pop{border-color:var(--brand);background:linear-gradient(180deg,rgba(46,108,246,.09),transparent)}
.price .badge{position:absolute;top:18px;right:18px;background:var(--grad);color:#fff;font-size:12px;font-weight:700;
  padding:4px 12px;border-radius:999px}
.price h3{font-size:20px;margin-bottom:6px}
.price .p-desc{color:var(--muted);font-size:14px;margin-bottom:18px;min-height:40px}
.price .p-price{font-size:40px;font-weight:900}
.price .p-price span{font-size:15px;color:var(--muted);font-weight:500}
.price ul{list-style:none;margin:20px 0 26px;display:flex;flex-direction:column;gap:12px}
.price ul li{display:flex;gap:10px;align-items:flex-start;font-size:14.5px;color:var(--muted)}
.price ul li::before{content:"✓";color:var(--green);font-weight:900}
.price .btn{width:100%}

/* calculator */
.calc{background:linear-gradient(180deg,var(--bg2),var(--bg));border-radius:26px;border:1px solid var(--card-brd);
  padding:34px;max-width:900px;margin:0 auto}
.calc-grid{display:grid;grid-template-columns:1.1fr 1fr;gap:30px;align-items:center}
.field{margin-bottom:20px}
.field label{display:block;font-size:14px;color:var(--muted);margin-bottom:10px}
.seg{display:flex;gap:8px;flex-wrap:wrap}
.seg button{flex:1;min-width:70px;padding:11px;border-radius:12px;background:var(--card);border:1px solid var(--card-brd);
  color:var(--muted);font-weight:600;cursor:pointer;transition:.2s;font-size:14px}
.seg button.on{background:var(--grad);color:#fff;border-color:transparent}
.calc input[type=range]{width:100%;accent-color:var(--brand);height:6px}
.calc .rangeval{font-weight:800;font-size:20px;color:var(--cyan)}
.result{background:var(--card);border:1px solid var(--card-brd);border-radius:var(--radius);padding:26px;text-align:center}
.result .big{font-size:44px;font-weight:900;line-height:1}
.result .save{color:var(--green);font-weight:700;margin-top:6px}
.result .row{display:flex;justify-content:space-between;padding:10px 0;border-top:1px dashed var(--card-brd);
  color:var(--muted);font-size:14px;margin-top:14px}
.result .row b{color:var(--txt)}
.calc-note{color:var(--muted);font-size:13px;margin-top:16px;line-height:1.7}

/* quick-buy */
.qk-box{max-width:900px;margin:0 auto}
.qk-addr{display:flex;align-items:center;gap:14px;flex-wrap:wrap;background:var(--card);border:1px solid rgba(46,230,200,.3);border-radius:16px;padding:18px 20px;margin-bottom:24px}
.qk-addr .lbl{color:var(--muted);font-size:13px;flex:none}
.qk-addr code{font-family:"SF Mono",Menlo,Consolas,monospace;color:var(--cyan);font-size:14.5px;word-break:break-all;flex:1;min-width:220px}
.qk-addr .btn{padding:9px 18px;font-size:13.5px}
.qk-qrwrap{flex:none;display:flex;flex-direction:column;align-items:center;gap:7px;margin:0 auto}
.qk-qr{width:122px;height:122px;background:#fff;border-radius:12px;padding:7px}
.qk-qr svg{width:100%;height:100%;display:block}
.qk-scan{color:var(--muted);font-size:12px}
.qk-reg{margin-top:16px;padding:14px 18px;border-radius:14px;background:rgba(46,108,246,.10);border:1px solid rgba(46,108,246,.30);color:#c7d5f8;font-size:14px;line-height:1.7}
.qk-reg a{color:var(--cyan);font-weight:700}
.qk-grid{display:grid;grid-template-columns:1fr 1fr;gap:20px}
.qk-card{background:var(--card);border:1px solid var(--card-brd);border-radius:var(--radius);padding:22px}
.qk-card h3{font-size:16px;margin-bottom:12px}
.qk-t{width:100%;border-collapse:collapse;font-size:14px}
.qk-t th,.qk-t td{text-align:left;padding:10px 8px;border-bottom:1px solid var(--card-brd)}
.qk-t th{color:var(--muted);font-weight:600;font-size:12px}
.qk-t td{color:#c3cce6}
.qk-t .amt{color:var(--cyan);font-weight:800;font-family:"SF Mono",Menlo,Consolas,monospace;white-space:nowrap}
.qk-warn{margin-top:22px;padding:14px 18px;border-radius:14px;background:rgba(255,91,69,.08);border:1px solid rgba(255,91,69,.35);color:#ffc2b8;font-size:14px;line-height:1.7;font-weight:600}
.qk-notes{margin-top:14px;list-style:none;display:flex;flex-direction:column;gap:8px;color:var(--muted);font-size:13.5px;line-height:1.8}
.qk-notes li{display:flex;gap:9px;align-items:flex-start}
.qk-notes li::before{content:"—";color:var(--cyan);flex:none}

/* API / docs building blocks */
.api-facts{display:grid;grid-template-columns:repeat(4,1fr);gap:14px;margin-bottom:30px}
.api-facts .fact{background:var(--card);border:1px solid var(--card-brd);border-radius:14px;padding:14px 16px;display:flex;flex-direction:column;gap:6px}
.api-facts .fl{color:var(--muted);font-size:12px}
.api-facts code{color:var(--cyan);font-family:"SF Mono",Menlo,Consolas,monospace;font-size:13px;word-break:break-all}
.ep{background:var(--card);border:1px solid var(--card-brd);border-radius:16px;padding:22px;margin-top:22px}
.ep-head{display:flex;align-items:center;gap:12px;flex-wrap:wrap}
.m-get{background:var(--green);color:#04110a;font-weight:900;font-size:12px;padding:4px 10px;border-radius:8px;letter-spacing:.5px}
.m-post{background:#3b82f6;color:#04110a;font-weight:900;font-size:12px;padding:4px 10px;border-radius:8px;letter-spacing:.5px}
.ep-path{font-family:"SF Mono",Menlo,Consolas,monospace;font-size:15px;color:#e8edfb;word-break:break-all}
.ep-name{color:var(--muted);font-size:14px}
.ep-desc{color:var(--muted);font-size:14px;margin:12px 0 18px;line-height:1.7}
.ep-grid{display:grid;grid-template-columns:1fr 1fr;gap:22px;align-items:start}
.ep-grid h5{font-size:13px;margin-bottom:8px;color:#e8edfb;letter-spacing:.3px}
.doc-t{width:100%;border-collapse:collapse;font-size:13px}
.doc-t th,.doc-t td{text-align:left;padding:9px 10px;border-bottom:1px solid var(--card-brd);vertical-align:top}
.doc-t th{color:var(--muted);font-weight:600;font-size:12px}
.doc-t code{color:var(--cyan);font-family:"SF Mono",Menlo,Consolas,monospace}
.doc-t td{color:#c3cce6;line-height:1.6}
.doc-t .req{color:var(--danger);font-weight:700}
.doc-t .opt{color:var(--muted)}
.err-t code{color:var(--danger);font-weight:700}
.err-t .ok{color:var(--green);font-weight:700}
.api-note{margin-top:22px;padding:14px 18px;border-radius:14px;background:rgba(46,230,200,.06);
  border:1px solid rgba(46,230,200,.22);color:var(--muted);font-size:13px;line-height:1.7}
.code{background:#070a12;border:1px solid var(--card-brd);border-radius:16px;overflow:hidden;font-size:13px}
.code .bar{display:flex;gap:7px;padding:13px 16px;border-bottom:1px solid var(--card-brd)}
.code .bar i{width:11px;height:11px;border-radius:50%}
.code pre{padding:18px;overflow-x:auto;line-height:1.7;font-family:"SF Mono",Menlo,Consolas,monospace;color:#cbd5f5}
.code .k{color:#ff8fa3}.code .s{color:#8ee7c5}.code .c{color:#6b7699}.code .n{color:#f7c66b}

/* docs two-column layout */
.docs-layout{display:grid;grid-template-columns:230px 1fr;gap:40px;align-items:start;padding:44px 0 90px}
.docs-side{position:sticky;top:86px;display:flex;flex-direction:column;gap:2px}
.docs-side .dgroup{color:var(--txt);font-size:12px;font-weight:800;letter-spacing:.8px;text-transform:uppercase;margin:16px 0 6px}
.docs-side .dgroup:first-child{margin-top:0}
.docs-side a{color:var(--muted);font-size:13.5px;padding:6px 10px;border-radius:8px;border-left:2px solid transparent;transition:.15s}
.docs-side a:hover{color:var(--txt);background:var(--card)}
.docs-side a.on{color:var(--cyan);border-left-color:var(--cyan);background:rgba(46,230,200,.06)}
.docs-side .dswitch{margin-top:22px;padding:12px 14px;border-radius:12px;background:var(--card);border:1px solid var(--card-brd);font-size:13px;color:var(--muted);line-height:1.7}
.docs-side .dswitch a{display:inline;padding:0;border:0;color:var(--cyan);font-weight:700}
.docs-main{min-width:0}
.docs-main h1{font-size:clamp(26px,4.5vw,36px);font-weight:900;letter-spacing:-.5px;margin-bottom:10px}
.docs-main .updated{color:var(--muted);font-size:13px;margin-bottom:26px}
.docs-main h2{font-size:22px;font-weight:800;margin:44px 0 14px;padding-top:10px;border-top:1px solid var(--card-brd)}
.docs-main h2:first-of-type{border-top:0;margin-top:8px;padding-top:0}
.docs-main h3{font-size:17px;font-weight:700;margin:26px 0 10px}
.docs-main p{color:var(--muted);font-size:14.5px;margin-bottom:12px;line-height:1.8}
.docs-main ul,.docs-main ol{color:var(--muted);font-size:14.5px;line-height:1.8;margin:0 0 14px 22px}
.docs-main li{margin-bottom:6px}
.docs-main strong{color:var(--txt)}
.docs-main a.inline{color:var(--cyan)}
.docs-main code{font-family:"SF Mono",Menlo,Consolas,monospace;font-size:13px;color:var(--cyan);
  background:rgba(46,230,200,.08);border:1px solid rgba(46,230,200,.18);border-radius:6px;padding:1px 6px}
.docs-main pre code{background:none;border:0;padding:0;color:inherit;font-size:inherit}
.docs-main .code{margin:14px 0 18px}
.docs-main .doc-t{margin:10px 0 18px}
.docs-main .api-note{margin:14px 0 18px}
.docs-main .warnbox{margin:14px 0 18px;padding:14px 18px;border-radius:14px;background:rgba(255,91,69,.08);
  border:1px solid rgba(255,91,69,.35);color:#ffc2b8;font-size:13.5px;line-height:1.7}
.docs-main .ep{margin:18px 0}

/* trust / faq / cta */
.trust{background:var(--card);border:1px solid var(--card-brd);border-radius:var(--radius);padding:26px 24px}
.trust h3{font-size:17px;margin-bottom:12px;display:flex;align-items:center;gap:9px}
.trust h3 .ic{width:34px;height:34px;border-radius:10px;background:rgba(46,230,200,.12);display:grid;place-items:center;font-size:17px;flex:none}
.trust p{color:var(--muted);font-size:14px;line-height:1.7}
.trust .more{margin-top:14px;display:inline-block;color:var(--cyan);font-weight:700;font-size:13.5px}
.faq{max-width:780px;margin:0 auto;display:flex;flex-direction:column;gap:12px}
.qa{background:var(--card);border:1px solid var(--card-brd);border-radius:14px;overflow:hidden}
.qa summary{padding:20px 22px;cursor:pointer;font-weight:600;font-size:16px;list-style:none;display:flex;
  justify-content:space-between;align-items:center;gap:14px}
.qa summary::-webkit-details-marker{display:none}
.qa summary::after{content:"+";font-size:24px;color:var(--cyan);transition:.2s}
.qa[open] summary::after{transform:rotate(45deg)}
.qa .a{padding:0 22px 20px;color:var(--muted);font-size:14.5px}
.cta-box{background:linear-gradient(135deg,rgba(46,108,246,.14),rgba(46,230,200,.12));border:1px solid var(--card-brd);
  border-radius:28px;padding:56px 34px;text-align:center;position:relative;overflow:hidden}
.cta-box h2{font-size:clamp(26px,5vw,38px);font-weight:900;margin-bottom:14px}
.cta-box p{color:var(--muted);margin-bottom:26px;font-size:16px}
.cta-box .cta-kefu-note{margin:16px 0 0;font-size:13px;color:var(--muted)}
.cta-box .cta-kefu-note a{color:var(--cyan)}

/* legal pages */
.legal{padding:56px 0 90px}
.legal .wrap{max-width:860px}
.legal h1{font-size:clamp(26px,5vw,38px);font-weight:900;letter-spacing:-.5px;margin-bottom:10px}
.legal .updated{color:var(--muted);font-size:13.5px;margin-bottom:40px}
.legal h2{font-size:20px;font-weight:800;margin:38px 0 12px}
.legal p{color:var(--muted);font-size:15px;margin-bottom:14px;line-height:1.8}
.legal ul{color:var(--muted);font-size:15px;line-height:1.8;margin:0 0 14px 22px}
.legal li{margin-bottom:6px}
.legal strong{color:var(--txt)}
.legal a.inline{color:var(--cyan)}
.legal code{font-family:"SF Mono",Menlo,Consolas,monospace;color:var(--cyan);font-size:13.5px;
  background:rgba(46,230,200,.08);border:1px solid rgba(46,230,200,.18);border-radius:6px;padding:1px 6px}
.infobox{background:var(--card);border:1px solid var(--card-brd);border-radius:var(--radius);padding:26px 24px;margin:8px 0 14px}
.inforow{display:flex;gap:14px;font-size:14.5px;color:var(--muted);padding:9px 0;border-bottom:1px dashed var(--card-brd);line-height:1.7}
.inforow:last-child{border-bottom:0}
.inforow .k{color:var(--txt);font-weight:600;min-width:96px;flex-shrink:0}
.inforow a{color:var(--cyan)}
.inforow code{font-family:"SF Mono",Menlo,Consolas,monospace;color:var(--cyan);font-size:13.5px}
.lead{background:var(--card);border:1px solid var(--card-brd);border-radius:var(--radius);padding:22px 24px;margin-bottom:12px}
.lead p{margin-bottom:0;font-size:15px}
.warn{background:rgba(255,91,69,.07);border:1px solid rgba(255,91,69,.28);border-radius:var(--radius);padding:20px 22px;margin:8px 0 14px}
.warn p{margin-bottom:0;color:#e8d3ce}
.warn strong{color:#fff}

/* footer */
footer{border-top:1px solid var(--card-brd);padding:50px 0 34px;margin-top:20px}
.foot{display:grid;grid-template-columns:1.6fr 1fr 1fr 1fr;gap:30px}
.foot h5{font-size:14px;margin-bottom:16px;color:var(--txt)}
.foot a{display:block;color:var(--muted);font-size:14px;margin-bottom:10px;transition:.2s}
.foot a:hover{color:var(--cyan)}
.foot .about p{color:var(--muted);font-size:14px;margin-top:12px;max-width:280px}
.foot-bottom{text-align:center;color:var(--muted);font-size:13px;margin-top:40px;padding-top:24px;border-top:1px solid var(--card-brd)}
.foot-nav{display:flex;justify-content:center;gap:24px;margin-bottom:18px;flex-wrap:wrap}
.foot-nav a{color:var(--muted);font-size:14px;transition:.2s}
.foot-nav a:hover{color:var(--cyan)}
.foot-friends{margin:26px 0 0}
.foot-friends span{color:var(--muted);font-size:14px;font-weight:600}

/* rendering performance: off-screen sections skip layout & paint */
.sec{content-visibility:auto;contain-intrinsic-size:auto 700px}
.ep{content-visibility:auto;contain-intrinsic-size:auto 520px}
footer{content-visibility:auto;contain-intrinsic-size:auto 420px}

/* responsive */
@media(max-width:1000px){
  .docs-layout{grid-template-columns:1fr;gap:20px}
  .docs-side{position:static;flex-direction:row;flex-wrap:wrap;gap:6px;background:var(--card);
    border:1px solid var(--card-brd);border-radius:14px;padding:12px}
  .docs-side .dgroup{width:100%;margin:6px 0 2px}
  .docs-side a{border-left:0;border:1px solid var(--card-brd)}
  .docs-side .dswitch{width:100%;margin-top:10px}
}
@media(max-width:920px){
  .calc-grid,.ep-grid{grid-template-columns:1fr;gap:24px}
  .steps,.feat-grid,.price-grid{grid-template-columns:1fr}
  .foot{grid-template-columns:1fr 1fr}
  .api-facts{grid-template-columns:1fr 1fr}
}
@media(max-width:820px){.qk-grid{grid-template-columns:1fr}}
@media(max-width:720px){
  .sec{padding:60px 0}
  .nav-links{display:none}
  .nav-cta .btn{display:none}
  .burger{display:flex}
  .nav-links.open{display:flex;position:absolute;top:66px;left:0;right:0;flex-direction:column;background:var(--bg2);
    padding:20px;gap:6px;border-bottom:1px solid var(--card-brd);z-index:60}
  .nav-links.open a{padding:12px 4px;width:100%;font-size:16px}
  .hero-stats{grid-template-columns:1fr 1fr}
  .calc{padding:22px}
  .result .big{font-size:36px}
  .lang button{padding:6px 9px}
}
@media(max-width:600px){.back-link{display:none}.inforow{flex-direction:column;gap:2px}}
@media(max-width:420px){
  .hero-stats{grid-template-columns:1fr 1fr;gap:10px}
  .foot{grid-template-columns:1fr}
}