This example demonstrates a basic SVG canvas with a solid red background, showcasing how CSS can style SVG elements. The code uses D3 v5 to select the SVG element and apply the background color directly via the `style` method. It also defines CSS rules for a `.lines` class, which sets stroke properties and uses `stroke-linejoin: round` for paths. The visualization is minimal, emphasizing the interplay between D3’s selection API and external stylesheets in a React framework context.