:root{--bg: #0e1116;--panel: #161b22;--panel2: #1f2630;--fg: #e6edf3;--muted: #7d8590;--accent: #58a6ff;--danger: #f85149;--ok: #3fb950;--border: #30363d;--split-x: 1fr;--split-y: 1.4fr}*{box-sizing:border-box}html,body{margin:0;padding:0;background:var(--bg);color:var(--fg);font:14px/1.5 -apple-system,BlinkMacSystemFont,Segoe UI,PingFang SC,sans-serif;height:100%}.topbar{display:flex;align-items:center;justify-content:space-between;padding:10px 16px;border-bottom:1px solid var(--border);background:var(--panel);flex-wrap:wrap;gap:8px}.topbar h1{margin:0;font-size:18px;letter-spacing:.5px}.controls{display:flex;gap:12px;align-items:center;flex-wrap:wrap}.controls label{display:flex;gap:6px;align-items:center;color:var(--muted)}button,select,input[type=text],input[type=password]{background:var(--panel2);color:var(--fg);border:1px solid var(--border);border-radius:6px;padding:6px 10px;font:inherit}button{cursor:pointer}button:hover{border-color:var(--accent)}.tab-radio{position:absolute;left:-9999px}.tabs{display:none;gap:6px;padding:8px 12px;border-bottom:1px solid var(--border);background:var(--panel)}.tabs label{flex:1;text-align:center;padding:8px;border:1px solid var(--border);border-radius:6px;cursor:pointer;color:var(--muted)}#tab-input:checked~.tabs label[for=tab-input],#tab-preview:checked~.tabs label[for=tab-preview],#tab-checklist:checked~.tabs label[for=tab-checklist]{background:var(--accent);color:#0d1117;border-color:var(--accent)}.grid{display:grid;grid-template-columns:var(--split-x) 6px var(--split-y) .9fr;gap:12px;padding:12px;height:calc(100vh - 56px)}.col{background:var(--panel);border:1px solid var(--border);border-radius:8px;padding:10px 12px;display:flex;flex-direction:column;min-width:0}.col h2{margin:0 0 8px;font-size:13px;color:var(--muted);text-transform:uppercase;letter-spacing:.5px}.row{display:flex;gap:8px;margin-top:8px;flex-wrap:wrap;align-items:center}textarea{flex:1;min-height:240px;resize:none;background:var(--bg);color:var(--fg);border:1px solid var(--border);border-radius:6px;padding:10px;font-family:ui-monospace,SF Mono,Menlo,monospace}.diagram{flex:1;overflow:auto;background:var(--bg);border:1px solid var(--border);border-radius:6px;padding:8px}.diagram svg{max-width:100%;height:auto}.error{background:#2d1115;border:1px solid var(--danger);color:#ffb4b4;padding:8px;border-radius:6px;margin-top:8px;white-space:pre-wrap;font-family:ui-monospace,monospace}.checklist-list{list-style:none;padding:0;margin:0;overflow:auto;flex:1}.checklist-list li{padding:6px 4px;border-bottom:1px dashed var(--border);display:flex;gap:8px;align-items:flex-start}.checklist-list li.done label{color:var(--muted);text-decoration:line-through}.splitter{background:var(--border);cursor:col-resize;border-radius:3px;transition:background .12s ease}.splitter:hover,.splitter.dragging{background:var(--accent)}.toast{background:var(--ok);color:#0d1117;padding:4px 10px;border-radius:999px;font-size:12px;transition:opacity .2s ease;opacity:1}.toast.fade{opacity:0}.modal{background:var(--panel);color:var(--fg);border:1px solid var(--border);border-radius:10px;max-width:480px;width:90vw}.modal::backdrop{background:#0009}.modal label{display:block;margin:10px 0}.modal input{width:100%;margin-top:4px}.modal menu{display:flex;gap:8px;justify-content:flex-end;padding:0;margin-top:12px}.warn{background:#1a2233;border:1px solid var(--accent);padding:8px;border-radius:6px;color:#cdd9ec;font-size:12px}@media (max-width: 900px){.tabs{display:flex}.grid{grid-template-columns:1fr;height:calc(100vh - 105px);padding:8px;gap:8px}.splitter,.col{display:none}#tab-input:checked~.grid .col[data-tab=input],#tab-preview:checked~.grid .col[data-tab=preview],#tab-checklist:checked~.grid .col[data-tab=checklist]{display:flex}textarea{min-height:160px}.topbar h1{font-size:16px}.controls{gap:6px}}