:root {
  --border: #e5e7eb;
  --text-muted: #6b7280;
  --text: #111827;
  --surface: #fff;
  --bg: #fafafa;
}
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
body{font-family:'Manrope','Newsreader',system-ui,sans-serif;background:var(--bg);color:var(--text);line-height:1.6;min-height:100vh}
.free-shell{display:flex;flex-direction:column;min-height:100vh}
.free-topbar{border-bottom:1px solid var(--border);background:var(--surface)}
.free-topbar-inner{display:flex;align-items:center;justify-content:space-between;max-width:1024px;margin:0 auto;padding:16px 24px}
.free-mark{display:flex;align-items:center;gap:8px}
.free-mark .integral{font-size:1.35rem}
.free-mark .wordmark{font-size:1rem;font-weight:600}
.free-mark .wordmark i{font-style:italic;font-weight:500}
.free-nav{display:flex;align-items:center;gap:16px;font-size:0.9rem}
.free-nav a{text-decoration:none;color:var(--text-muted);transition:color .15s}
.free-nav a:hover{color:var(--text)}
.free-nav .free-cta{padding:6px 16px;background:#111827;color:#fff;border-radius:6px;font-weight:600}
.free-nav .free-cta:hover{background:#374151;color:#fff}
.free-paper{max-width:1024px;margin:0 auto;padding:0 24px;flex:1;width:100%}
.free-paper__meta{font-size:.75rem;font-family:'JetBrains Mono',monospace;letter-spacing:.08em;text-transform:uppercase;color:var(--text-muted);max-width:1024px;margin:0 auto;padding:24px 24px 0;width:100%}
.wrap{max-width:1024px;margin:0 auto;padding:0 24px}
.free-footer{border-top:1px solid var(--border);background:var(--surface);margin-top:auto}
.free-footer-inner{max-width:1024px;margin:0 auto;padding:24px;font-size:.82rem;color:var(--text-muted);display:flex;justify-content:space-between;align-items:center}
.btn{display:inline-flex;align-items:center;gap:6px;padding:10px 22px;border-radius:8px;font-size:.95rem;font-weight:600;text-decoration:none;cursor:pointer;transition:background .15s,border-color .15s}
.btn-primary{background:#111827;color:#fff;border:1px solid #111827}
.btn-primary:hover{background:#374151}
.btn-ghost{background:transparent;color:var(--text);border:1px solid var(--border)}
.btn-ghost:hover{background:#f9fafb}
.arrow{font-size:1.1em;transition:transform .15s}
.btn-primary:hover .arrow{transform:translateX(3px)}