:root{--bg:#f6f8fc;--card:#fff;--ink:#172033;--muted:#667085;--brand:#3a55d1;--purple:#6e46c7;--teal:#137d79;--soft:#edf1ff;--line:#dfe4ee;--good:#edf8f4;--shadow:0 14px 38px rgba(39,52,100,.08)}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;font-family:Inter,system-ui,-apple-system,"Segoe UI",sans-serif;color:var(--ink);background:var(--bg);line-height:1.62}a{color:var(--brand);text-decoration:none}a:hover{text-decoration:underline}
header{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.95);backdrop-filter:blur(12px);border-bottom:1px solid var(--line)}.nav{max-width:1180px;margin:auto;padding:13px 20px;display:flex;align-items:center;justify-content:space-between;gap:18px}.brand{display:flex;align-items:center;gap:10px;font-weight:900;color:var(--ink)}.brand img{width:36px;height:36px}.navlinks{display:flex;gap:15px;flex-wrap:wrap;font-size:.94rem}
.hero{max-width:1180px;margin:auto;padding:68px 20px 42px;display:grid;grid-template-columns:1.12fr .88fr;gap:30px;align-items:center}.eyebrow{text-transform:uppercase;letter-spacing:.11em;font-weight:850;font-size:.77rem;color:var(--brand)}.hero h1{font-size:clamp(2.65rem,6vw,5.5rem);line-height:.98;margin:10px 0 18px;letter-spacing:-.045em}.hero p{font-size:1.13rem;color:var(--muted);max-width:760px}
.hero-card,.card,.calc,.article,.formula-box,.example-box{background:var(--card);border:1px solid var(--line);border-radius:20px;box-shadow:var(--shadow)}.hero-card{padding:25px}.hero-card h3{margin-top:0}.hero-grid{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin-top:18px}.mini{padding:14px;border-radius:14px;background:var(--soft)}.mini b{display:block;font-size:1.25rem}
.container{max-width:1180px;margin:auto;padding:0 20px 64px}.section-title{font-size:2.08rem;margin:7px 0 8px}.section-sub{color:var(--muted);margin:0 0 22px}.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}.grid2{display:grid;grid-template-columns:repeat(2,1fr);gap:18px}.card{padding:22px}.card h3{margin:0 0 7px}.card p{color:var(--muted)}
.tag{display:inline-block;background:var(--soft);color:var(--brand);padding:5px 9px;border-radius:999px;font-size:.76rem;font-weight:850;margin-bottom:10px}.tag.purple{background:#f3edff;color:var(--purple)}.tag.teal{background:#e9f7f5;color:var(--teal)}
.btn{display:inline-block;border:0;border-radius:11px;padding:11px 16px;background:var(--brand);color:#fff;font:inherit;font-weight:800;cursor:pointer}.btn.secondary{background:#fff;color:var(--brand);border:1px solid var(--brand)}.btn:hover{text-decoration:none;filter:brightness(.97)}
.article{max-width:900px;margin:36px auto 64px;padding:30px}.article h1{font-size:clamp(2.15rem,5vw,3.7rem);line-height:1.05;letter-spacing:-.03em;margin-bottom:14px}.article h2{margin-top:34px}.breadcrumbs{font-size:.88rem;color:var(--muted);margin-bottom:12px}
.calc{padding:24px;margin:22px 0}.calc-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:16px}.calc-grid.three{grid-template-columns:repeat(3,1fr)}.calc-grid.four{grid-template-columns:repeat(4,1fr)}label{display:block;font-weight:760;font-size:.94rem;margin-bottom:6px}input,select,textarea{width:100%;padding:11px 12px;border:1px solid #cbd3e1;border-radius:10px;background:#fff;font:inherit;color:var(--ink)}
.result{margin-top:18px;padding:18px;border-radius:14px;background:var(--good);border:1px solid #cfe6dc}.result.error{background:#fff0ef;border-color:#efc8c5}.metric{font-size:1.65rem;font-weight:900;color:var(--brand)}.small{font-size:.88rem;color:var(--muted)}
.formula-box{padding:20px;margin:20px 0;background:linear-gradient(135deg,#f8f9ff,#f4f0ff)}.formula{font-family:Georgia,"Times New Roman",serif;font-size:1.5rem}.example-box{padding:20px;margin:18px 0}.note{margin:20px 0;padding:15px 17px;border-left:4px solid var(--brand);background:var(--soft);border-radius:10px}
.steps{counter-reset:step;padding-left:0}.steps li{list-style:none;position:relative;padding-left:44px;margin:16px 0}.steps li:before{counter-increment:step;content:counter(step);position:absolute;left:0;top:0;width:30px;height:30px;border-radius:50%;background:var(--brand);color:#fff;display:grid;place-items:center;font-weight:850}
.table-wrap{overflow-x:auto}table{width:100%;border-collapse:collapse;margin:18px 0}th,td{padding:11px 10px;border-bottom:1px solid var(--line);text-align:left}th{background:#eef2fb}
footer{background:#fff;border-top:1px solid var(--line);padding:30px 20px;color:var(--muted)}.footer-inner{max-width:1180px;margin:auto;display:flex;justify-content:space-between;gap:20px;flex-wrap:wrap}.footer-links{display:flex;gap:14px;flex-wrap:wrap}
@media(max-width:850px){.hero{grid-template-columns:1fr;padding-top:46px}.grid,.grid2{grid-template-columns:1fr}.calc-grid,.calc-grid.three,.calc-grid.four{grid-template-columns:1fr}.nav{align-items:flex-start}.navlinks{justify-content:flex-end}}