:root{--paper:#f7f9fa;--surface:#fff;--ink:#1c2733;--circuit:#2a5caa;--pass:#1f7a4d;--signal:#d9730d;--comment:#8593a8;--grid-line:#e8edf2;--border:#dce3ea}*{box-sizing:border-box}body,html{margin:0;min-height:100%}body{background-color:var(--paper);background-image:linear-gradient(var(--grid-line) 1px,transparent 1px),linear-gradient(90deg,var(--grid-line) 1px,transparent 1px);background-size:12px 12px;color:var(--ink);font-family:Arial,Noto Sans SC,sans-serif}a{color:var(--circuit)}.page-shell{min-height:100vh}.topbar{height:56px;display:flex;align-items:center;justify-content:space-between;padding:0 24px;background:var(--surface);border-bottom:1px solid var(--border)}.eyebrow,.logo,.repl-input-row,.repl-window,.window-bar{font-family:JetBrains Mono,ui-monospace,monospace}.logo{font-weight:500}.topbar nav{display:flex;gap:24px}.reading-column{width:min(720px,calc(100% - 32px));margin:0 auto;padding:72px 0}.eyebrow{color:var(--comment);font-size:12px;letter-spacing:.08em}h1{font-size:clamp(26px,5vw,38px);font-weight:500;margin:12px 0 32px}.paper-card,.repl-window{background:var(--surface);border:1px solid var(--border);border-radius:12px}.repl-window{overflow:hidden}.window-bar{display:flex;justify-content:space-between;padding:12px 16px;color:var(--comment);border-bottom:1px solid var(--border);font-size:12px}.repl-input-row{display:flex;align-items:center;gap:12px;padding:22px 16px;color:var(--circuit)}.repl-input-row input{width:100%;border:0;outline:0;background:transparent;color:var(--ink);font:inherit;font-size:14px}.paper-card{margin-top:24px;padding:32px}.empty-prompt{color:var(--comment);font-family:LXGW WenKai Screen,Noto Sans SC,serif;line-height:1.85}:focus-visible{outline:2px solid var(--circuit);outline-offset:2px}@media (max-width:639px){.topbar{padding:0 16px}.reading-column{width:calc(100% - 24px);padding:48px 0}.paper-card{padding:24px}}