:root{--bg:#f8f9fb;--fg:#222;--muted:#6b7280;--brand:#0ea5e9}*{box-sizing:border-box}html,body,#root{height:100%;overflow:hidden}body{margin:0;font-family:ui-sans-serif,system-ui,Segoe UI,Roboto,Arial;color:var(--fg);background:var(--bg)}.app{display:flex;flex-direction:column;height:100%}header{flex:0 0 auto;display:flex;align-items:center;justify-content:space-between;padding:12px 16px;background:#fff;border-bottom:1px solid #e5e7eb}h1{font-size:18px;margin:0}.toolbar{display:flex;gap:8px;align-items:center}.toolbar select,.toolbar button{padding:6px 10px}main{flex:1;min-height:0;display:grid;grid-template-columns:280px minmax(0,1fr) 320px;gap:12px;padding:12px;overflow:hidden}.panel{overflow-y:auto;background:#fff;border:1px solid #e5e7eb;border-radius:8px;padding:12px}.panel h3{margin:8px 0}.panel label{display:block;font-size:13px;color:var(--muted);margin:8px 0}.panel input{width:100%;padding:6px 8px;margin-top:4px}.canvas{overflow:auto;background:#fff;border:1px solid #e5e7eb;border-radius:8px;padding:12px;display:flex;align-items:center;justify-content:center}ul{padding-left:16px}