This example demonstrates a reusable horizontal split view interface for organizing content into two resizable panels within a D3.js application. The view renders an upper and lower content area, separated by a draggable resizing marker that users can adjust to change each panel’s height. Built on D3 v7 and React, the code uses closures to manage layout state and render functions, with the tabbed view and blank layout modules providing additional structural context. The example highlights a modular approach to building flexible, nested UI components using D3’s DOM manipulation capabilities.