:root{--primary:#007bff;--bg:#f0f2f5;--panel:#fff;--border:#d9dee5;--text:#212529;--muted:#6c757d}body{margin:0;padding:20px;background:var(--bg);color:var(--text);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif}.container{display:grid;grid-template-columns:320px 1fr;gap:20px;max-width:1400px;margin:0 auto}.controls,.canvas-panel{background:var(--panel);border:1px solid var(--border);border-radius:12px;padding:18px}h1{font-size:24px;margin-top:0}label,input,select,button{display:block;width:100%;box-sizing:border-box}input,select,button{margin:10px 0;padding:10px;border-radius:8px;border:1px solid var(--border);background:var(--panel);color:var(--text)}button{background:var(--primary);color:#fff;border:none;cursor:pointer;font-weight:600}.file-list{display:grid;gap:8px;margin-top:12px}.file-item{padding:8px 10px;background:rgba(0,0,0,0.03);border-radius:8px;font-size:14px}.canvas-panel{display:flex;justify-content:center;align-items:center;overflow:auto;min-height:80vh;background-image:linear-gradient(45deg,#eee 25%,transparent 25%),linear-gradient(-45deg,#eee 25%,transparent 25%),linear-gradient(45deg,transparent 75%,#eee 75%),linear-gradient(-45deg,transparent 75%,#eee 75%);background-size:20px 20px;background-position:0 0,0 10px,10px -10px,-10px 0}canvas{max-width:100%;height:auto;border-radius:8px}.dark-mode{--primary:#3d8bfd;--bg:#1e2128;--panel:#2a2e37;--border:#4a505f;--text:#e5e7eb;--muted:#9ca3af}.dark-mode .file-item{background:rgba(255,255,255,0.04)}.dark-mode .canvas-panel{background-image:linear-gradient(45deg,#2a2e37 25%,transparent 25%),linear-gradient(-45deg,#2a2e37 25%,transparent 25%),linear-gradient(45deg,transparent 75%,#2a2e37 75%),linear-gradient(-45deg,transparent 75%,#2a2e37 75%)}@media(max-width:900px){body{padding:10px}.container{grid-template-columns:1fr}.canvas-panel{min-height:50vh}}