This chart displays calcium concentration levels for a single patient over time. A red vertical line indicates the currently selected date, and hovering over the chart triggers a tooltip that shows the exact date and value. The visualization is built with D3 version 5, using `d3.line`, `d3.scaleTime`, `d3.scaleLinear`, and `d3.axisBottom`/`d3.axisLeft` to render the axes and line within an SVG container. Data is loaded from a CSV file containing multiple medical markers, though only the calcium series is displayed.