This stacked bar chart visualizes the distribution of letter grades (A, B, C, D) across five school subjects, using data from a CSV file. Built with D3 v7, it renders as an SVG with color-coded bars separated by subject. The visualization uses `d3.csv` for data loading, `d3.stack` to create the stacked segments, `d3.scaleBand` for the categorical y-axis, and `d3.scaleLinear` for the percentage x-axis. A tooltip displays the exact grade percentage when hovering over a segment.