Resizable Horizontal Split component design & features
This example uses the shadcn Resizable component with a horizontal ResizablePanelGroup, two ResizablePanel children, and a ResizableHandle between them. Each panel uses defaultSize to start at 50% width.
Horizontal splits are the default layout for side-by-side content such as sidebars, split editors, and preview panes where users need to adjust the relative width of two regions.