:root{
  --bg:#f6f8fc;
  --surface:#ffffff;
  --surface-2:#f9fbff;
  --text:#0e1a2f;
  --muted:#5a6b85;
  --line:#e3e9f2;
  --brand:#2563eb;
  --brand-2:#4f46e5;
  --brand-soft:#eef4ff;
  --accent:#0ea5a4;
  --shadow-sm:0 1px 2px rgba(15,30,60,.05),0 4px 14px rgba(15,30,60,.05);
  --shadow-md:0 12px 32px rgba(20,45,90,.10);
  --radius:18px;
  --max:1160px;
}
*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{
  margin:0;
  font-family:"Segoe UI",system-ui,-apple-system,"Helvetica Neue",Arial,sans-serif;
  background:var(--bg);
  color:var(--text);
  line-height:1.6;
  font-size:16px;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
img,svg{display:block;max-width:100%}
a{color:inherit;text-decoration:none}
button{font:inherit}
h1,h2,h3,h4,p{margin-top:0}
.container{width:min(100% - 40px,var(--max));margin-inline:auto}
section{scroll-margin-top:92px}
:focus-visible{outline:3px solid rgba(37,99,235,.45);outline-offset:3px;border-radius:8px}

.skip-link{
  position:fixed;top:-60px;left:16px;z-index:200;
  background:var(--brand);color:#fff;padding:10px 16px;border-radius:10px;font-weight:600;
  transition:top .2s;
}
.skip-link:focus{top:12px}

/* ---------- Header ---------- */
.site-header{
  position:sticky;top:0;z-index:60;
  background:rgba(255,255,255,.88);
  -webkit-backdrop-filter:blur(14px);
  backdrop-filter:blur(14px);
  border-bottom:1px solid var(--line);
}
.header-inner{display:flex;align-items:center;gap:20px;height:50px}
.brand{display:flex;align-items:center;gap:11px;flex-shrink:0}
.logo{
  width:38px;height:38px;border-radius:12px;
  background:linear-gradient(135deg,#2563eb,#6d28d9);
  display:grid;place-items:center;
  box-shadow:0 6px 16px rgba(37,99,235,.28);
  flex-shrink:0;
}
.logo svg{width:22px;height:22px}
.brand-text strong{display:block;font-size:16px;letter-spacing:-.015em;line-height:1.25}
.brand-text small{display:block;font-size:11.5px;color:var(--muted);line-height:1.25}
.main-nav{display:flex;align-items:center;gap:26px;margin-left:auto;font-size:14.5px;font-weight:500;color:#384a63}
.nav-links{display:flex;align-items:center;gap:26px}
.main-nav a{padding:6px 0;transition:color .18s}
.main-nav a:hover{color:var(--brand)}
.main-nav a[aria-current="page"]{color:var(--brand);font-weight:700}
.header-actions{display:flex;align-items:center;gap:10px;flex-shrink:0;margin-left:0}
.offcanvas-head,.offcanvas-foot{display:none}
.nav-backdrop{display:none}
/* backdrop-filter creates a containing block for fixed children.
   Disable it while the offcanvas is open so the panel covers the viewport. */
.site-header.nav-open{-webkit-backdrop-filter:none;backdrop-filter:none}

.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:9px;
  padding:13px 22px;border-radius:12px;border:1px solid transparent;
  font-weight:600;font-size:15px;cursor:pointer;white-space:nowrap;
  transition:transform .18s ease,box-shadow .18s ease,background .18s ease,border-color .18s ease;
}
.btn-primary{
  background:linear-gradient(135deg,#2563eb,#4f46e5);
  color:#fff;box-shadow:0 10px 24px rgba(37,99,235,.26);
}
.btn-primary:hover{transform:translateY(-1px);box-shadow:0 14px 30px rgba(37,99,235,.34)}
.btn-ghost{background:#fff;border-color:var(--line);color:#243754;box-shadow:var(--shadow-sm)}
.btn-ghost:hover{border-color:#c9d6ea;background:#fbfdff}
.btn-sm{padding:9px 15px;border-radius:10px;font-size:13.5px}
.btn svg{width:17px;height:17px;flex-shrink:0}

/* Language */
.lang{position:relative}
.lang-btn{
  display:inline-flex;align-items:center;gap:7px;
  background:#fff;border:1px solid var(--line);border-radius:10px;
  padding:8px 11px;font-size:13px;font-weight:600;color:#2b3d58;
  cursor:pointer;box-shadow:var(--shadow-sm);
  transition:border-color .18s,background .18s;
}
.lang-btn:hover{border-color:#c9d6ea;background:#fbfdff}
.lang-btn svg{width:16px;height:16px;color:var(--muted)}
.lang-btn .chev{width:13px;height:13px;transition:transform .18s}
.lang.open .lang-btn .chev{transform:rotate(180deg)}
.lang-menu{
  position:absolute;right:0;top:calc(100% + 10px);z-index:80;
  width:224px;max-width:calc(100vw - 32px);
  margin:0;padding:7px;list-style:none;
  background:#fff;border:1px solid var(--line);border-radius:14px;
  box-shadow:0 18px 44px rgba(20,45,90,.16);
  opacity:0;visibility:hidden;transform:translateY(-6px);
  transition:opacity .16s,transform .16s,visibility .16s;
}
.lang.open .lang-menu{opacity:1;visibility:visible;transform:none}
.lang-menu button{
  width:100%;display:flex;align-items:center;gap:10px;
  padding:9px 10px;border:0;border-radius:9px;background:transparent;
  font-size:13.5px;font-weight:500;color:#2b3d58;cursor:pointer;text-align:left;
}
.lang-menu button:hover,.lang-menu button:focus-visible{background:var(--brand-soft)}
.lang-code{
  width:31px;height:24px;border-radius:6px;background:#f1f5fb;
  display:grid;place-items:center;font-size:10.5px;font-weight:700;
  letter-spacing:.04em;color:#4a5f7d;flex-shrink:0;
}
.lang-menu button[aria-selected="true"] .lang-code{background:#e2edff;color:var(--brand)}
.lang-menu .check{margin-left:auto;width:15px;height:15px;color:var(--brand);opacity:0;flex-shrink:0}
.lang-menu button[aria-selected="true"] .check{opacity:1}

.nav-toggle{
  display:none;width:40px;height:40px;border-radius:10px;
  border:1px solid var(--line);background:#fff;color:#2b3d58;
  place-items:center;cursor:pointer;box-shadow:var(--shadow-sm);
}
.nav-toggle svg{width:20px;height:20px}
.nav-toggle .close-ico{display:none}
.site-header.nav-open .nav-toggle .open-ico{display:none}
.site-header.nav-open .nav-toggle .close-ico{display:block}

/* ---------- Hero ---------- */
.hero{position:relative;overflow:hidden;padding:16px 0 28px}
.hero::before{
  content:"";position:absolute;inset:-22% -10% auto;height:760px;pointer-events:none;
  background:
    radial-gradient(620px 340px at 78% 16%,rgba(37,99,235,.14),transparent 66%),
    radial-gradient(520px 300px at 10% 0%,rgba(124,58,237,.10),transparent 62%);
}
.hero-grid{position:relative;display:grid;grid-template-columns:1.04fr .96fr;gap:56px;align-items:center}
.eyebrow{
  display:inline-flex;align-items:center;gap:8px;
  background:#fff;border:1px solid #dbe6fa;border-radius:999px;
  padding:6px 13px;font-size:12.5px;font-weight:600;color:#31527f;
  box-shadow:var(--shadow-sm);margin-bottom:22px;
}
.eyebrow .dot{width:7px;height:7px;border-radius:50%;background:#16a34a;box-shadow:0 0 0 4px rgba(22,163,74,.12)}
.hero h1{
  font-size:clamp(2.15rem,5vw,3.6rem);
  line-height:1.07;letter-spacing:-.035em;margin:0 0 20px;font-weight:800;
}
.hero h1 span{display:block}
.accent{
  background:linear-gradient(118deg,#2563eb 0%,#7c3aed 58%,#0ea5a4 100%);
  -webkit-background-clip:text;background-clip:text;color:transparent;
}
.hero-desc{font-size:1.06rem;color:var(--muted);max-width:560px;margin:0 0 28px}
.hero-actions{display:flex;flex-wrap:wrap;gap:12px;margin-bottom:20px}
.hero-note{display:flex;align-items:center;gap:8px;font-size:13px;color:#66788f;margin:0}
.hero-note svg{width:15px;height:15px;color:#16a34a;flex-shrink:0}
.hero-stats{display:flex;flex-wrap:wrap;gap:14px 34px;margin-top:34px;padding-top:26px;border-top:1px solid var(--line)}
.stat strong{display:block;font-size:1.35rem;line-height:1.2;letter-spacing:-.02em}
.stat span{font-size:12.5px;color:var(--muted)}

/* Mock editor */
.hero-visual{position:relative}
.mock{
  position:relative;background:#fff;border:1px solid var(--line);
  border-radius:20px;padding:14px;
  box-shadow:0 30px 64px -24px rgba(24,49,96,.28);
  transform:rotate(.6deg);
}
.mock-bar{display:flex;align-items:center;gap:10px;padding:2px 4px 12px}
.dots{display:flex;gap:5px}
.dots i{width:8px;height:8px;border-radius:50%;background:#e2e8f0}
.dots i:nth-child(1){background:#fca5a5}
.dots i:nth-child(2){background:#fcd34d}
.dots i:nth-child(3){background:#86efac}
.mock-title{font-size:11.5px;font-weight:600;color:#7b8ba4;letter-spacing:.02em}
.mock-pill{
  margin-left:auto;font-size:10px;font-weight:700;letter-spacing:.08em;
  color:var(--brand);background:var(--brand-soft);padding:3px 8px;border-radius:6px;
}
.mock-tools{display:flex;gap:6px;padding:0 4px 12px;flex-wrap:wrap}
.mock-tools span{
  width:32px;height:28px;display:grid;place-items:center;
  background:#f6f9ff;border:1px solid #e6edfa;border-radius:7px;
  font-family:"Cambria Math","Times New Roman",serif;font-size:14px;color:#47648d;
}
.mock-canvas{
  position:relative;overflow:hidden;
  background:linear-gradient(180deg,#fbfdff,#f4f8ff);
  border:1px solid #e8eefb;border-radius:14px;
  padding:26px 18px 10px;
}
.formula{
  display:flex;align-items:center;justify-content:center;gap:8px;
  font-family:"Cambria Math","Times New Roman",Georgia,serif;
  font-size:clamp(21px,2.6vw,29px);color:#16233b;line-height:1;
}
.formula .big{font-size:1.5em;line-height:.8;transform:translateY(-2px)}
.lims{display:inline-flex;flex-direction:column;font-size:.46em;line-height:1.15;margin-left:-.18em}
.lims span:first-child{transform:translateY(-1px)}
.frac{display:inline-flex;flex-direction:column;text-align:center;font-size:.74em;line-height:1.12}
.frac>span:first-child{border-bottom:1.5px solid currentColor;padding:0 .24em .07em}
.frac>span:last-child{padding-top:.07em}
.op{padding:0 .1em;color:#3b5b8a}
.mock-graph{margin-top:16px;width:100%;height:auto}
.float-card{
  position:absolute;z-index:2;background:#fff;border:1px solid var(--line);
  border-radius:11px;padding:8px 12px;font-size:11.5px;font-weight:700;
  color:#31527f;box-shadow:0 10px 24px rgba(24,49,96,.14);
  display:flex;align-items:center;gap:7px;
}
.float-card .fc-dot{width:7px;height:7px;border-radius:50%;background:var(--brand)}
.fc1{top:52px;right:-16px;transform:rotate(-2deg)}
.fc2{bottom:64px;left:-20px;transform:rotate(1.5deg)}
.fc2 .fc-dot{background:var(--accent)}
/* ---------- Sections ---------- */
.section{padding:82px 0}
.section-head{max-width:690px;margin:0 auto;text-align:center}
.section-head h2{
  font-size:clamp(1.6rem,3.4vw,2.3rem);
  letter-spacing:-.03em;line-height:1.15;margin:0 0 14px;font-weight:800;
}
.section-head p{color:var(--muted);font-size:15.5px;margin:0}
.section-alt{background:linear-gradient(180deg,rgba(255,255,255,.6),rgba(255,255,255,0))}

.features-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:20px;margin-top:44px}
.feature{
  background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);
  padding:26px 24px;box-shadow:var(--shadow-sm);
  transition:transform .2s ease,box-shadow .2s ease,border-color .2s ease;
}
.feature:hover{transform:translateY(-3px);box-shadow:var(--shadow-md);border-color:#d7e3f6}
.feature .icon{
  width:44px;height:44px;border-radius:12px;background:var(--brand-soft);
  color:var(--brand);display:grid;place-items:center;margin-bottom:16px;
}
.feature .icon svg{width:22px;height:22px}
.feature h3{font-size:16.5px;margin:0 0 8px;letter-spacing:-.01em}
.feature p{font-size:14px;color:var(--muted);margin:0}

/* Tools */
.tools-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:18px;margin-top:44px}
.tool{
  position:relative;display:flex;flex-direction:column;
  background:var(--surface);border:1px solid var(--line);border-radius:16px;
  padding:22px;box-shadow:var(--shadow-sm);min-height:222px;
  transition:transform .2s ease,box-shadow .2s ease,border-color .2s ease;
}
.tool:hover{transform:translateY(-4px);box-shadow:var(--shadow-md);border-color:#cfdef5}
.tool-top{display:flex;align-items:center;justify-content:space-between;gap:10px;margin-bottom:16px}
.tool-icon{
  width:42px;height:42px;border-radius:11px;display:grid;place-items:center;
  background:linear-gradient(135deg,#eff5ff,#f4f0ff);color:var(--brand);flex-shrink:0;
}
.tool-icon svg{width:21px;height:21px}
.tool-tag{
  font-size:9.5px;letter-spacing:.09em;text-transform:uppercase;font-weight:700;
  color:#4f46e5;background:#f2f0ff;padding:4px 8px;border-radius:999px;white-space:nowrap;
}
.tool h3{font-size:15.5px;margin:0 0 8px;line-height:1.3;letter-spacing:-.01em}
.tool p{font-size:13.2px;color:var(--muted);margin:0 0 18px;flex:1}
.tool-open{
  display:inline-flex;align-items:center;gap:6px;
  font-size:12.8px;font-weight:600;color:var(--brand);margin-top:auto;
}
.tool-open svg{width:14px;height:14px;transition:transform .18s}
.tool:hover .tool-open svg{transform:translateX(3px)}

/* Steps */
.steps{display:grid;grid-template-columns:repeat(3,1fr);gap:22px;margin-top:46px;position:relative}
.step{position:relative;text-align:center;padding:0 14px}
.step-num{
  width:46px;height:46px;border-radius:50%;margin:0 auto 18px;
  display:grid;place-items:center;font-weight:800;font-size:17px;
  color:var(--brand);background:#fff;border:1px solid #d8e4f8;
  box-shadow:0 6px 18px rgba(37,99,235,.13);position:relative;z-index:1;
}
.step h3{font-size:16.5px;margin:0 0 8px}
.step p{font-size:14px;color:var(--muted);margin:0 auto;max-width:300px}
.steps::before{
  content:"";position:absolute;top:23px;left:16%;right:16%;height:1px;
  background:linear-gradient(90deg,transparent,#dbe6fa 18%,#dbe6fa 82%,transparent);
}

/* FAQ */
.faq-list{max-width:820px;margin:42px auto 0;display:grid;gap:12px}
.faq-item{
  background:#fff;border:1px solid var(--line);border-radius:14px;
  padding:0 20px;box-shadow:var(--shadow-sm);
}
.faq-item summary{
  list-style:none;cursor:pointer;padding:17px 0;font-weight:600;font-size:15px;
  display:flex;align-items:center;justify-content:space-between;gap:16px;
}
.faq-item summary::-webkit-details-marker{display:none}
.faq-item summary::after{
  content:"+";font-size:21px;font-weight:400;color:var(--brand);
  line-height:1;transition:transform .2s ease;flex-shrink:0;
}
.faq-item[open] summary::after{transform:rotate(45deg)}
.faq-item p{margin:0 0 18px;color:var(--muted);font-size:14.2px;padding-right:24px}

/* CTA */
.cta-section{padding:20px 0 84px}
.cta-box{
  position:relative;overflow:hidden;text-align:center;
  background:linear-gradient(135deg,#eef4ff,#f6f1ff 55%,#eefaf8);
  border:1px solid #dbe6fa;border-radius:26px;padding:56px 36px;
}
.cta-box::before,.cta-box::after{
  content:"";position:absolute;border-radius:50%;pointer-events:none;
}
.cta-box::before{width:280px;height:280px;top:-140px;right:-80px;background:rgba(37,99,235,.07)}
.cta-box::after{width:220px;height:220px;bottom:-130px;left:-60px;background:rgba(14,165,164,.08)}
.cta-box h2{font-size:clamp(1.55rem,3.2vw,2.15rem);letter-spacing:-.03em;margin:0 0 12px;font-weight:800;position:relative}
.cta-box p{color:var(--muted);max-width:540px;margin:0 auto 26px;position:relative}
.cta-box .btn{position:relative}

/* Footer */
.site-footer{background:#fff;border-top:1px solid var(--line);padding:56px 0 28px;margin-top:20px}
.footer-grid{display:grid;grid-template-columns:1.6fr repeat(4,1fr);gap:34px}
.footer-brand p{font-size:13.5px;color:var(--muted);max-width:300px;margin:14px 0 0}
.footer-col h4{font-size:12px;letter-spacing:.09em;text-transform:uppercase;color:#7b8ba4;margin:0 0 14px;font-weight:700}
.footer-col ul{list-style:none;margin:0;padding:0;display:grid;gap:9px}
.footer-col a{font-size:13.5px;color:#425673;transition:color .18s}
.footer-col a:hover{color:var(--brand)}
.footer-bottom{
  display:flex;align-items:center;justify-content:space-between;gap:16px;flex-wrap:wrap;
  border-top:1px solid var(--line);margin-top:42px;padding-top:22px;
  font-size:12.5px;color:var(--muted);
}
.footer-bottom .lang-note{display:flex;align-items:center;gap:6px}
.footer-bottom .lang-note svg{width:14px;height:14px}

/* Reveal */
.js .reveal{opacity:0;transform:translateY(16px);transition:opacity .55s ease,transform .55s ease}
.js .reveal.in{opacity:1;transform:none}

/* ---------- Responsive ---------- */
@media (max-width:1100px){
  .tools-grid{grid-template-columns:repeat(3,1fr)}
}
@media (max-width:980px){
  .hero-grid{grid-template-columns:1fr;gap:48px}
  .hero-desc{max-width:640px}
  .hero-visual{max-width:560px;margin:0 auto;width:100%}
  .features-grid{grid-template-columns:repeat(2,1fr)}
  .footer-grid{grid-template-columns:1.4fr 1fr 1fr;gap:30px}
  .footer-brand{grid-column:1 / -1}
}
@media (max-width:920px){
  body.nav-locked{overflow:hidden}
  .nav-toggle{display:grid}
  .header-actions{margin-left:auto}
  .header-cta{display:none}
  .brand-text small{display:none}
  .nav-backdrop{
    display:block;position:fixed;inset:0;z-index:80;
    background:rgba(14,26,47,.42);
    -webkit-backdrop-filter:blur(2px);backdrop-filter:blur(2px);
    opacity:0;visibility:hidden;transition:opacity .24s ease,visibility .24s ease;
  }
  .site-header.nav-open .nav-backdrop{opacity:1;visibility:visible}
  .main-nav{
    position:fixed;top:0;right:0;bottom:0;left:auto;z-index:90;
    width:min(340px,86vw);max-width:100%;
    margin:0;padding:0;display:flex;flex-direction:column;align-items:stretch;gap:4px;
    background:#fff;border:0;border-left:1px solid var(--line);
    border-radius:0;box-shadow:-24px 0 60px rgba(20,45,90,.18);
    overflow-y:auto;overscroll-behavior:contain;
    transform:translateX(102%);visibility:hidden;
    transition:transform .28s cubic-bezier(.32,.72,0,1),visibility .28s;
  }
  .site-header.nav-open .main-nav{transform:none;visibility:visible}
  .offcanvas-head{
    display:flex;align-items:center;justify-content:space-between;gap:12px;
    padding:18px 18px 16px;border-bottom:1px solid var(--line);margin-bottom:8px;
  }
  .offcanvas-head .brand-text strong{font-size:15px}
  .offcanvas-title{font-size:11px;font-weight:700;letter-spacing:.12em;text-transform:uppercase;color:#8a9bb4;margin:0}
  .offcanvas-close{
    width:36px;height:36px;border-radius:10px;border:1px solid var(--line);
    background:#fff;color:#2b3d58;display:grid;place-items:center;cursor:pointer;
  }
  .offcanvas-close svg{width:17px;height:17px}
  .nav-links{display:flex;flex-direction:column;align-items:stretch;gap:2px;padding:0 12px}
  .main-nav a{
    padding:13px 14px;border-radius:11px;font-size:15.5px;font-weight:600;
    color:#26374f;display:flex;align-items:center;justify-content:space-between;gap:10px;
  }
  .main-nav a::after{
    content:"";width:7px;height:7px;border-right:1.8px solid #b3c1d4;
    border-top:1.8px solid #b3c1d4;transform:rotate(45deg);flex-shrink:0;
  }
  .main-nav a:hover,.main-nav a:focus-visible{background:var(--brand-soft);color:var(--brand)}
  .main-nav a[aria-current="page"]{background:var(--brand-soft);color:var(--brand)}
  .main-nav a[aria-current="page"]::after{border-color:var(--brand)}
  .offcanvas-foot{
    display:block;margin-top:auto;padding:20px 18px 24px;
  }
  .offcanvas-foot .btn{width:100%}
  .offcanvas-foot p{margin:12px 0 0;font-size:12px;color:var(--muted);text-align:center}
}
@media (min-width:921px){
  .offcanvas-head,.offcanvas-foot,.nav-backdrop{display:none !important}
}
@media (max-width:860px){
  .tools-grid{grid-template-columns:repeat(2,1fr)}
  .steps{grid-template-columns:1fr;gap:34px;max-width:460px;margin-inline:auto}
  .steps::before{display:none}
}
@media (max-width:720px){
  .section{padding:66px 0}
  .hero{padding:4px 0 6px}
  .features-grid{grid-template-columns:1fr}
  .footer-grid{grid-template-columns:1fr 1fr}
  .footer-brand{grid-column:2 / 4}
  .hero-stats{gap:18px 26px}
  .cta-box{padding:44px 22px}
  .float-card{display:none}
}
@media (max-width:560px){
  .container{width:calc(100% - 32px)}
  .header-inner{height:64px;gap:12px}
  .brand-text strong{font-size:14.5px}
  .logo{width:34px;height:34px;border-radius:10px}
  .logo svg{width:19px;height:19px}
  .lang-btn{padding:7px 9px}
  .lang-btn #langCode{font-size:11.5px}
  .tools-grid{grid-template-columns:1fr}
  .tool{min-height:0}
  .hero-actions .btn{flex:1 1 auto}
  .hero-stats{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}
  .stat strong{font-size:1.15rem}
  .footer-grid{grid-template-columns:1fr;gap:28px}
  .footer-bottom{flex-direction:column;align-items:flex-start}
  .mock-canvas{padding:22px 12px 8px}
  .formula{gap:5px}
}
.view-switch{margin:0 0 36px;text-align:center;font-size:13px}
.view-switch a{color:#5f7390;text-decoration:underline;text-underline-offset:3px}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .js .reveal{opacity:1;transform:none;transition:none}
  *{transition-duration:.01ms !important;animation-duration:.01ms !important}
}