:root{
  --ink:#0f2233; --ink2:#33506b; --accent:#0e7c86; --accent2:#f59e0b;
  --bg:#f6f8fa; --card:#ffffff; --line:#d9e2ec; --muted:#5b7186;
}
*{box-sizing:border-box}
body{margin:0;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  color:var(--ink);background:var(--bg);line-height:1.6}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
header.site{background:var(--ink);color:#fff}
.wrap{max-width:1060px;margin:0 auto;padding:0 20px}
header.site .wrap{display:flex;align-items:center;justify-content:space-between;padding-top:16px;padding-bottom:16px}
.logo{font-weight:800;font-size:22px;color:#fff;letter-spacing:.02em}
.logo span{color:var(--accent2)}
nav a{color:#cfe3f2;margin-left:20px;font-size:15px}
nav a:hover{color:#fff;text-decoration:none}
.hero{background:linear-gradient(160deg,var(--ink) 0%,#17405f 70%,#0e7c86 130%);color:#fff;padding:56px 0 48px}
.hero h1{font-size:36px;line-height:1.2;margin:0 0 12px}
.hero p{font-size:18px;color:#d7e6f2;max-width:720px;margin:0 0 22px}
.btn{display:inline-block;background:var(--accent2);color:#231a00;font-weight:700;
  padding:12px 22px;border-radius:10px;font-size:16px}
.btn:hover{text-decoration:none;filter:brightness(1.06)}
.btn.ghost{background:transparent;border:2px solid #9fc3dd;color:#eaf4fb;margin-left:10px}
.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(300px,1fr));gap:20px;margin:34px 0}
.card{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:22px}
.card h3{margin:0 0 8px;font-size:19px}
.card p{margin:0 0 12px;color:var(--ink2)}
.tag{display:inline-block;background:#e6f4f5;color:var(--accent);font-size:12px;font-weight:700;
  padding:3px 9px;border-radius:99px;margin-bottom:10px;text-transform:uppercase;letter-spacing:.05em}
section.block{padding:10px 0 6px}
h2.sec{font-size:26px;margin:26px 0 6px}
p.lede{color:var(--ink2);max-width:760px}
footer.site{border-top:1px solid var(--line);margin-top:44px;padding:22px 0 40px;color:var(--muted);font-size:13px}
/* calculator */
.calc{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:24px;margin:26px 0}
.calc h2{margin-top:0}
.fields{display:grid;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));gap:14px 22px}
.field label{display:block;font-size:13px;font-weight:700;color:var(--ink2);margin-bottom:4px}
.field input,.field select{width:100%;padding:10px;border:1px solid var(--line);border-radius:8px;font-size:16px;background:#fffbe8}
.field .unit{font-size:12px;color:var(--muted)}
.results{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:14px;margin-top:22px}
.result{background:#eef6fb;border:1px solid #c8deee;border-radius:12px;padding:14px 16px}
.result .k{font-size:12px;font-weight:700;text-transform:uppercase;letter-spacing:.05em;color:var(--ink2)}
.result .v{font-size:26px;font-weight:800}
.result .u{font-size:14px;color:var(--ink2);font-weight:600}
.note{font-size:13px;color:var(--muted)}
/* article */
article.guide{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:30px;margin:26px 0}
article.guide h1{font-size:30px;line-height:1.25;margin:0 0 6px}
article.guide h2{font-size:22px;margin:28px 0 6px}
article.guide table{border-collapse:collapse;width:100%;margin:14px 0}
article.guide th,article.guide td{border:1px solid var(--line);padding:8px 10px;text-align:left;font-size:15px}
article.guide th{background:#eef6fb}
.cta{background:#fff7e6;border:1px solid #f3d189;border-radius:12px;padding:18px 20px;margin:26px 0}
.cta h3{margin:0 0 6px}