:root{--bg: #0f1115;--surface: #171a21;--border: #2a2f3a;--text: #e8eaed;--muted: #8b93a1;--accent: #5b8cff;--accent-soft: #5b8cff33;--node-fill: #1f2430;--node-stroke: #3a4152;--node-selected: #5b8cff;--edge: #454d5e;--danger: #ff5b6a}*{box-sizing:border-box}html,body{margin:0;height:100%;background:var(--bg);color:var(--text);font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica,Arial,sans-serif;overflow:hidden}#app{display:flex;flex-direction:column;height:100%}#toolbar{display:flex;align-items:center;gap:20px;padding:10px 16px;background:var(--surface);border-bottom:1px solid var(--border);flex-wrap:wrap}.toolbar-group{display:flex;align-items:center;gap:8px}.brand{font-weight:600;font-size:15px;color:var(--text);margin-right:4px}button{background:var(--node-fill);color:var(--text);border:1px solid var(--border);border-radius:6px;padding:6px 12px;font-size:13px;cursor:pointer;transition:background .15s,border-color .15s}button:hover{background:#262b38;border-color:var(--accent)}button:active{transform:translateY(1px)}#btn-delete:hover{border-color:var(--danger);color:var(--danger)}#canvas-wrap{flex:1;position:relative;overflow:hidden;background:radial-gradient(var(--border) 1px,transparent 1px);background-size:24px 24px;background-position:0 0}#canvas{width:100%;height:100%;cursor:grab}#canvas.panning{cursor:grabbing}.node-group{cursor:pointer}.node-rect{fill:var(--node-fill);stroke:var(--node-stroke);stroke-width:1.5;transition:stroke .1s,fill .1s}.node-group.selected .node-rect{stroke:var(--node-selected);stroke-width:2.5;fill:#232a3d}.node-group.root .node-rect{fill:var(--accent);stroke:var(--accent)}.node-group.root .node-text{fill:#fff;font-weight:600}.node-text{fill:var(--text);font-size:14px;font-family:inherit;user-select:none;pointer-events:none;dominant-baseline:middle}.edge{fill:none;stroke:var(--edge);stroke-width:2}.node-edit-input{background:var(--node-fill);color:var(--text);border:1px solid var(--accent);border-radius:4px;font-size:14px;font-family:inherit;padding:2px 6px;outline:none;width:100%;height:100%}#hint{padding:6px 16px;font-size:12px;color:var(--muted);background:var(--surface);border-top:1px solid var(--border)}