This bar chart visualizes the distribution of CSS levels across a dataset of colors, showing how many colors correspond to each specification level. The chart uses a vertical bar layout with hover effects that change bar color from steelblue to orange. Built with D3 v7, the visualization loads CSV data from a GitHub gist, aggregates counts with `d3.rollup`, and renders the chart as an SVG using `d3.scaleBand` for the x-axis and `d3.scaleLinear` for the y-axis. Axis labels and rotated x-axis tick text clarify the categorical and numeric values.