:root{--bg:#fff;--fg:#1f2328;--muted:#656d76;--border:#d0d7de;--accent:#0969da;--sidebar:#f6f8fa;--mark:#fff3a3}*{box-sizing:border-box}body,html{margin:0;padding:0}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica,Arial,sans-serif;color:var(--fg);background:var(--bg);font-size:14px;line-height:1.6}a{color:var(--accent);text-decoration:none}a:hover{text-decoration:underline}mark{background:var(--mark)}.layout{display:flex;min-height:100vh}.sidebar{width:280px;flex-shrink:0;background:var(--sidebar);border-right:1px solid var(--border);padding:16px;overflow-y:auto}.main{flex:1 1;padding:28px 40px;max-width:900px}.brand{font-weight:700;font-size:16px;margin-bottom:16px}.section-title{font-size:11px;text-transform:uppercase;letter-spacing:.04em;color:var(--muted);margin:18px 0 6px}.tree{padding-left:0}.tree,.tree ul{list-style:none;margin:0}.tree ul{padding-left:14px}.tree a{display:block;padding:3px 6px;border-radius:6px;color:var(--fg)}.tree a:hover{background:#eaeef2;text-decoration:none}.tree a.active{background:#ddf4ff;color:var(--accent)}button,input,textarea{font:inherit;border:1px solid var(--border);border-radius:6px;padding:7px 10px;background:#fff}button{background:var(--accent);color:#fff;border-color:var(--accent);cursor:pointer}button.secondary{background:#fff;color:var(--fg)}.row{display:flex;gap:8px;align-items:center}.muted{color:var(--muted)}.card,.editor{border:1px solid var(--border);border-radius:8px;padding:16px}.editor{min-height:320px}.editor:focus-within{border-color:var(--accent)}.ProseMirror:focus{outline:none}.ProseMirror h1{font-size:1.6em}.ProseMirror h2{font-size:1.3em}.center{max-width:360px;margin:12vh auto}.error{color:#cf222e}.comment{border-top:1px solid var(--border);padding:10px 0}.savestate{font-size:12px;color:var(--muted)}