Two SVG canvases demonstrate basic line drawing with D3 v5. The first shows a single fixed red line, while the second uses `d3.select` and `.enter().append('line')` to map an array of seven numeric values to multiple blue and green lines with varying coordinates. The blue lines position themselves horizontally based on array index, while green lines stagger vertically. Both use SVG attributes like `x1`, `y1`, `x2`, and `y2` with inline stroke styles, rendered against light and dark gray backgrounds. The page loads D3 from a CDN and renders purely as vector SVG without animation or interaction.