:root{--bg:#fff;--fg:#171717;--muted:#6b7280;--line:#e5e7eb;--accent:#1f2937;--maxw:1080px}*{box-sizing:border-box}html,body{margin:0;padding:0}body{background:var(--bg);color:var(--fg);-webkit-font-smoothing:antialiased;font-family:Pretendard,-apple-system,BlinkMacSystemFont,Segoe UI,system-ui,sans-serif;line-height:1.7}a{color:inherit;text-decoration:none}.container{max-width:var(--maxw);margin:0 auto;padding:0 20px}.site-header{border-bottom:1px solid var(--line);background:var(--bg);z-index:50;position:sticky;top:0}.header-inner{align-items:center;gap:24px;height:64px;display:flex}.brand{font-size:18px;font-weight:700}.nav{color:var(--muted);gap:20px;margin-left:8px;font-size:14px;display:flex}.nav a:hover{color:var(--fg)}.cta-group{gap:8px;margin-left:auto;display:flex}.btn{border:1px solid #0000;border-radius:8px;padding:8px 14px;font-size:14px;font-weight:600;display:inline-block}.btn-primary{background:var(--accent);color:#fff}.btn-ghost{border-color:var(--line);color:var(--fg)}.hero h1{letter-spacing:-.02em;margin:0 0 20px;font-size:44px;line-height:1.25}.hero p{color:var(--muted);max-width:640px;margin:0 0 28px;font-size:18px}.eyebrow{color:var(--muted);margin:0 0 12px;font-size:13px;font-weight:700}section.block{border-top:1px solid var(--line);padding:64px 0}section.block h2{letter-spacing:-.01em;margin:0 0 12px;font-size:26px}section.block>.container>p{color:var(--muted);max-width:720px}.grid{gap:20px;margin-top:28px;display:grid}.grid-2{grid-template-columns:repeat(2,minmax(0,1fr))}.grid-3{grid-template-columns:repeat(3,minmax(0,1fr))}@media (max-width:760px){.grid-2,.grid-3{grid-template-columns:1fr}.hero h1{font-size:32px}.nav{display:none}}.card{border:1px solid var(--line);border-radius:12px;padding:22px}.card h3{margin:0 0 8px;font-size:17px}.card p{color:var(--muted);margin:0;font-size:15px}.todo{color:#92400e;background:#fffbeb;border-left:3px solid #f59e0b;border-radius:0 8px 8px 0;padding:12px 16px;font-size:14px}.site-footer{border-top:1px solid var(--line);color:var(--muted);margin-top:40px;padding:40px 0;font-size:14px}.footer-brand{color:var(--fg);margin:0 0 6px;font-weight:700}.footer-meta,.footer-note{margin:0 0 4px}.diagram{width:100%;height:auto;margin-top:28px}.dg-box{fill:var(--surface);stroke:var(--line);stroke-width:1px}.dg-zone{fill:none;stroke:var(--line);stroke-width:1px;stroke-dasharray:6 5}.dg-title{fill:var(--fg);font-size:15px;font-weight:700}.dg-sub{fill:var(--muted);font-size:13px}.dg-zonelabel{fill:var(--accent);letter-spacing:.02em;font-size:12px;font-weight:700}.dg-arrow{stroke:var(--muted);stroke-width:1.5px;fill:none}.dg-arrowhead{fill:var(--muted)}:root{--surface:#fafafa;--accent:#1d4ed8}.eyebrow{text-transform:none;letter-spacing:.04em;color:var(--accent)}.hero{padding:104px 0 80px}.hero h1{letter-spacing:-.03em}.btn-primary{background:var(--accent)}.btn-primary:hover{filter:brightness(.92)}.card{background:var(--surface);transition:border-color .15s}.card:hover{border-color:#d1d5db}section.block h2{font-size:28px}section.block ul,section.block ol{color:var(--muted);padding-left:20px}section.block li{margin:6px 0}section.block li::marker{color:var(--accent)}.brand{letter-spacing:-.02em}