This scatter plot visualizes CSS color specifications, mapping each named color’s CSS level (1 through 4) on the x-axis against its computed luminance (brightness) on the y-axis. Each circle is filled with its corresponding hex value, revealing how brightness varies across specification releases. The code uses d3.csv to load color data from a GitHub gist, then applies d3.scaleLinear for both axes, d3.axisBottom and d3.axisLeft for ticks, and SVG circles with custom hex-to-luminance conversion. The chart also rotates x-axis labels and includes axis titles for readability.