:root{
  --bg:#f6f8fb;
  --card:#ffffff;
  --text:#15202b;
  --muted:#667085;
  --line:#e7eaf0;
  --brand:#2f80ed;
  --brand2:#56ccf2;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Hiragino Kaku Gothic ProN",
  "Yu Gothic",Meiryo,sans-serif;
  background:var(--bg); color:var(--text); line-height:1.75;
}
a{color:var(--brand); text-decoration:none}
a:hover{text-decoration:underline}
header{
  position:sticky; top:0; z-index:10;
  background:rgba(255,255,255,.92); backdrop-filter:blur(12px);
  border-bottom:1px solid var(--line);
}
.nav{
  max-width:980px; margin:auto; padding:14px 20px;
  display:flex; align-items:center; justify-content:space-between; gap:16px;
}
.brand{font-weight:800; font-size:22px; letter-spacing:-.02em}
.brand span{
  display:inline-block; width:12px; height:12px; border-radius:4px;
  background:linear-gradient(135deg,var(--brand),var(--brand2)); margin-right:9px;
}
.navlinks{display:flex; gap:18px; font-size:14px; flex-wrap:wrap}
main{max-width:900px; margin:auto; padding:44px 20px 72px}
.hero{
  background:linear-gradient(135deg,#ffffff 0%,#eef6ff 100%);
  border:1px solid var(--line); border-radius:24px; padding:38px;
  box-shadow:0 10px 30px rgba(15,23,42,.05);
}
h1{font-size:40px; line-height:1.25; margin:0 0 14px; letter-spacing:-.03em}
h2{font-size:24px; margin-top:38px; line-height:1.4}
h3{font-size:18px; margin-top:28px}
p,li{font-size:16px}
.lead{font-size:18px;color:var(--muted);max-width:700px}
.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;margin-top:28px}
.card{
  background:var(--card); border:1px solid var(--line); border-radius:18px;
  padding:22px; box-shadow:0 8px 24px rgba(15,23,42,.04);
}
.card h3{margin:0 0 8px}
.small{font-size:14px;color:var(--muted)}
.footer{
  border-top:1px solid var(--line); padding:26px 20px 40px; color:var(--muted);
  text-align:center; font-size:14px;
}
.badge{
  display:inline-block; padding:6px 10px; border-radius:999px;
  background:#eaf4ff; color:#1769aa; font-size:13px; font-weight:700; margin-bottom:14px;
}
.content{
  background:#fff;border:1px solid var(--line);border-radius:20px;padding:30px;
}
ul,ol{padding-left:1.4em}
code{background:#f2f4f7;padding:.15em .4em;border-radius:6px}
@media(max-width:720px){
  h1{font-size:32px}
  .grid{grid-template-columns:1fr}
  .nav{align-items:flex-start; flex-direction:column}
  .navlinks{gap:12px}
  .hero,.content{padding:24px}
  main{padding-top:28px}
}