This sunburst chart visualizes hierarchical sequences from a CSV of page-access paths, showing the proportion of visits that begin with each sequence. Hovering over an arc highlights its ancestor path in the breadcrumb trail and displays the percentage of total visits it represents, while fading unrelated segments. Built with D3 v4, it uses `d3.partition()`, `d3.arc()`, and `d3.hierarchy()` to compute the radial layout, with colors from `d3.schemeTableau10`. The data is parsed from CSV rows into a tree structure via `d3.csvParseRows()`. Mouseover and mouseleave events drive the interactive highlighting and opacity transitions.