*{box-sizing:border-box;margin:0;padding:0}body{font-family:-apple-system,system-ui,sans-serif}.app{background:#fafafa;flex-direction:column;height:100vh;display:flex}header{background:#fff;border-bottom:1px solid #e8e8ed;align-items:baseline;gap:16px;padding:16px 24px;display:flex}h1{font-size:18px;font-weight:700}.count{color:#888;margin-left:auto;font-size:13px}.pane{flex:1;grid-template-columns:1fr 1fr;gap:0;display:grid;overflow:hidden}textarea{resize:none;background:#fff;border:0;border-right:1px solid #e8e8ed;outline:0;padding:32px;font-family:ui-monospace,SF Mono,Menlo,monospace;font-size:15px;line-height:1.7}.preview{background:#fff;padding:32px;line-height:1.7;overflow-y:auto}.preview h1,.preview h2,.preview h3{margin:24px 0 12px}.preview h1{border-bottom:2px solid #e8e8ed;padding-bottom:8px;font-size:28px}.preview h2{font-size:22px}.preview h3{font-size:18px}.preview p{margin:12px 0}.preview a{color:#4f46e5;text-decoration:none}.preview a:hover{text-decoration:underline}.preview code{color:#c026d3;background:#f0f0f8;border-radius:4px;padding:2px 6px;font-family:ui-monospace,monospace;font-size:.92em}.preview pre{color:#f5f5fa;background:#1a1a1f;border-radius:8px;padding:16px 20px;font-family:ui-monospace,monospace;font-size:14px;overflow-x:auto}.preview blockquote{color:#555;background:#f0f0f8;border-left:4px solid #6366f1;margin:12px 0;padding:4px 16px}.preview ul{margin:12px 0;padding-left:24px}.preview li{margin:4px 0}