双栏实时编辑Live split-pane editing
左侧写 Markdown 源码,右侧实时预览,输入 300ms 防抖后自动渲染;GFM 表格与任务列表开箱即用,预览里点击任务复选框还能反向回写源码。 Write Markdown on the left, see it rendered on the right — the preview refreshes 300ms after you stop typing. GFM tables and task lists just work, and clicking a task checkbox in the preview writes the change back into your source.