:root{
  --bg:#ffffff;
  --ink:#111;
  --muted:#60636b;
  --line:#e7e7ef;
  --card:#f7f8fb;
  --accent:#007aff; /* iOS-ish blue (not a trademark element) */
}
*{box-sizing:border-box}
html{font-size:16px}
body{margin:0;font-family:ui-sans-serif,system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,"Noto Sans JP","Hiragino Kaku Gothic ProN",Meiryo,sans-serif;color:var(--ink);background:var(--bg);line-height:1.7;letter-spacing:.02em}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
.container{max-width:980px;margin:0 auto;padding:24px}
.header{display:flex;align-items:center;justify-content:space-between;padding:14px 24px;border-bottom:1px solid var(--line);position:sticky;top:0;background:rgba(255,255,255,.9);backdrop-filter:saturate(160%) blur(6px)}
.brand{display:flex;align-items:center;gap:10px;color:var(--ink);text-decoration:none}
.brand svg{width:30px;height:30px}
.brand .title{font-weight:800}
.nav a{margin-left:16px;color:var(--muted)}
.hero{padding:56px 24px 24px}
.hero h1{font-size:clamp(1.8rem,3vw,2.6rem);margin:0 0 10px}
.hero p{margin:0;color:var(--muted)}
.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}
.card{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:16px}
.card h3{margin:0 0 8px;font-size:1rem}
.card p{margin:0;color:var(--muted)}
.footer{border-top:1px solid var(--line);padding:24px;color:var(--muted);font-size:.92rem}
.main{padding:24px}
.prose h1,.prose h2{line-height:1.3}
.prose h2{margin-top:1.4em}
.note{font-size:.92rem;color:var(--muted)}
.kbd{font-family:ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono","Courier New", monospace;background:#f2f2f6;border:1px solid var(--line);border-radius:6px;padding:2px 6px}
@media (max-width:760px){.grid{grid-template-columns:1fr}}