:root{
  --bg:#f6f7fb;--surface:#ffffff;--surface-2:#f0f2f8;--text:#14182b;--muted:#5a6178;
  --border:#e1e4ee;--brand:#1f5eff;--brand-2:#0a3fd1;--brand-soft:#e8efff;--accent:#00a37a;
  --warn-bg:#fff7e6;--warn-border:#f3c46b;--radius:14px;--shadow:0 1px 2px rgba(20,24,43,.05),0 8px 24px rgba(20,24,43,.06);
  --font:system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
}
@media (prefers-color-scheme:dark){:root{
  --bg:#0e1120;--surface:#161a2e;--surface-2:#1d2239;--text:#eef0f8;--muted:#a3a9c2;
  --border:#2a3050;--brand:#6f95ff;--brand-2:#9db6ff;--brand-soft:#1d2a55;--accent:#3fd3a6;
  --warn-bg:#2b2412;--warn-border:#7a5d1d;--shadow:none;
}}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--text);font:16px/1.65 var(--font)}
a{color:var(--brand)}a:hover{color:var(--brand-2)}
img,svg{max-width:100%}
.wrap{max-width:1120px;margin:0 auto;padding:0 16px}
.skip{position:absolute;left:-999px}.skip:focus{left:16px;top:8px;background:var(--surface);padding:8px;z-index:9}

/* header */
.top{background:var(--surface);border-bottom:1px solid var(--border);position:sticky;top:0;z-index:5}
.top .wrap{display:flex;align-items:center;gap:16px;min-height:62px}
.logo{display:flex;align-items:center;gap:9px;font-weight:800;font-size:1.15rem;color:var(--text);text-decoration:none;letter-spacing:-.01em}
.logo svg{width:30px;height:30px;flex:none}
.logo span b{color:var(--brand)}
.nav{display:flex;gap:4px;margin-left:auto;align-items:center}
.nav a{color:var(--muted);text-decoration:none;padding:8px 10px;border-radius:9px;font-size:.95rem}
.nav a:hover{background:var(--surface-2);color:var(--text)}
.lang{position:relative}
.lang summary{list-style:none;cursor:pointer;padding:7px 11px;border:1px solid var(--border);border-radius:9px;font-size:.9rem;color:var(--text);white-space:nowrap}
.lang summary::-webkit-details-marker{display:none}
.lang ul{position:absolute;right:0;top:calc(100% + 6px);margin:0;padding:6px;list-style:none;background:var(--surface);border:1px solid var(--border);border-radius:12px;box-shadow:var(--shadow);min-width:210px}
.lang li a{display:block;padding:8px 10px;border-radius:8px;color:var(--text);text-decoration:none;font-size:.93rem}
.lang li a:hover,.lang li a[aria-current]{background:var(--brand-soft)}
@media (max-width:760px){.nav .hide-m{display:none}}

/* breadcrumbs */
.crumbs{font-size:.86rem;color:var(--muted);margin:18px 0 0}
.crumbs ol{list-style:none;padding:0;margin:0;display:flex;flex-wrap:wrap;gap:6px}
.crumbs li+li::before{content:"›";margin-right:6px}
.crumbs a{color:var(--muted)}

/* hero */
.hero{padding:42px 0 18px}
.hero h1{font-size:clamp(1.7rem,4vw,2.6rem);line-height:1.15;margin:0 0 12px;letter-spacing:-.02em}
.hero p{color:var(--muted);font-size:1.08rem;max-width:720px;margin:0}
.badges{display:flex;flex-wrap:wrap;gap:8px;margin-top:18px}
.badge{background:var(--surface);border:1px solid var(--border);padding:6px 11px;border-radius:999px;font-size:.85rem;color:var(--muted)}

/* grid of tools */
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:14px;margin:22px 0 40px}
.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:20px;text-decoration:none;color:var(--text);box-shadow:var(--shadow);transition:transform .15s,border-color .15s;display:block}
.card:hover{transform:translateY(-2px);border-color:var(--brand)}
.card .ico{font-size:1.6rem;line-height:1}
.card h2,.card h3{font-size:1.07rem;margin:10px 0 6px;color:var(--text)}
.card p{margin:0;color:var(--muted);font-size:.93rem}

/* tool */
.tool{display:grid;grid-template-columns:1.1fr .9fr;gap:18px;margin:6px 0 30px}
@media (max-width:860px){.tool{grid-template-columns:1fr}}
.panel{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:22px;box-shadow:var(--shadow)}
.panel h2{font-size:1.1rem;margin:0 0 14px}
.fields{display:grid;grid-template-columns:1fr 1fr;gap:14px}
@media (max-width:520px){.fields{grid-template-columns:1fr}}
.f{display:flex;flex-direction:column;gap:6px}
.f.full{grid-column:1/-1}
.f label{font-weight:600;font-size:.92rem}
.f .hint{font-size:.8rem;color:var(--muted)}
.inp{display:flex;align-items:stretch;border:1px solid var(--border);border-radius:10px;background:var(--surface-2);overflow:hidden}
.inp:focus-within{border-color:var(--brand);box-shadow:0 0 0 3px var(--brand-soft)}
.inp input,.inp select{flex:1;min-width:0;border:0;background:transparent;color:var(--text);font:inherit;padding:10px 12px;outline:0}
.inp select{cursor:pointer}
.inp .u{display:flex;align-items:center;padding:0 12px;color:var(--muted);font-size:.86rem;border-left:1px solid var(--border);white-space:nowrap}
.chk{display:flex;gap:9px;align-items:flex-start;font-size:.93rem;cursor:pointer}
.chk input{margin-top:4px;width:17px;height:17px;accent-color:var(--brand)}
.result{position:sticky;top:80px;align-self:start}
.big{background:linear-gradient(135deg,var(--brand),var(--brand-2));color:#fff;border-radius:12px;padding:18px 20px;margin-bottom:14px}
.big small{display:block;opacity:.85;font-size:.88rem}
.big output{display:block;font-size:2rem;font-weight:800;letter-spacing:-.02em;line-height:1.2;margin-top:4px}
@media (prefers-color-scheme:dark){.big{color:#0e1120}}
.rows{margin:0;padding:0;list-style:none}
.rows li{display:flex;justify-content:space-between;gap:10px;padding:10px 0;border-bottom:1px dashed var(--border);font-size:.95rem}
.rows li:last-child{border:0}
.rows span{color:var(--muted)}
.rows output{font-weight:700;text-align:right}
.note{font-size:.84rem;color:var(--muted);margin:12px 0 0}
.warn{background:var(--warn-bg);border:1px solid var(--warn-border);border-radius:10px;padding:10px 12px;font-size:.88rem;margin-top:12px}
table.data{width:100%;border-collapse:collapse;font-size:.92rem;margin:10px 0}
table.data th,table.data td{border-bottom:1px solid var(--border);padding:8px 6px;text-align:left}
table.data th{color:var(--muted);font-weight:600}
.tbl{overflow-x:auto}

/* article */
.content{display:grid;grid-template-columns:minmax(0,1fr) 300px;gap:28px;margin-bottom:40px}
@media (max-width:960px){.content{grid-template-columns:1fr}}
article.prose{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:28px}
@media (max-width:520px){article.prose{padding:20px}}
.prose h2{font-size:1.35rem;margin:28px 0 10px;letter-spacing:-.01em}
.prose h2:first-child{margin-top:0}
.prose h3{font-size:1.08rem;margin:20px 0 8px}
.prose p,.prose li{color:var(--text)}
.prose code,.formula{background:var(--surface-2);border:1px solid var(--border);border-radius:8px;padding:2px 6px;font-family:ui-monospace,Consolas,monospace;font-size:.9em}
.formula{display:block;padding:12px 14px;margin:10px 0;overflow-x:auto}
.faq details{border:1px solid var(--border);border-radius:10px;padding:0 14px;margin:8px 0;background:var(--surface-2)}
.faq summary{cursor:pointer;font-weight:600;padding:12px 0}
.faq details p{margin:0 0 12px}
aside.side .panel{margin-bottom:14px}
aside.side ul{margin:0;padding:0;list-style:none}
aside.side li a{display:block;padding:8px 0;border-bottom:1px solid var(--border);text-decoration:none}
.updated{font-size:.85rem;color:var(--muted);margin-top:24px}

/* footer */
footer.foot{background:var(--surface);border-top:1px solid var(--border);padding:30px 0;margin-top:20px;font-size:.92rem;color:var(--muted)}
.foot .cols{display:grid;grid-template-columns:2fr 1fr 1fr;gap:20px}
@media (max-width:700px){.foot .cols{grid-template-columns:1fr}}
.foot h4{margin:0 0 8px;color:var(--text);font-size:.95rem}
.foot ul{list-style:none;margin:0;padding:0}
.foot li{margin:4px 0}
.foot a{color:var(--muted);text-decoration:none}.foot a:hover{color:var(--brand)}
.foot .copy{border-top:1px solid var(--border);margin-top:20px;padding-top:16px;font-size:.85rem}

/* language chooser on root */
.locales{display:grid;grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:12px;margin:24px 0 50px}
.locales a{display:flex;gap:12px;align-items:center;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:16px;text-decoration:none;color:var(--text);font-weight:600;box-shadow:var(--shadow)}
.locales a:hover{border-color:var(--brand)}
.locales .fl{font-size:1.6rem}
.locales small{display:block;color:var(--muted);font-weight:400}
.suggest{background:var(--brand-soft);border:1px solid var(--brand);border-radius:12px;padding:12px 16px;margin-top:16px;display:none}