This line chart displays the daily temperature variation over a week in San Francisco, using a single line to trace the temperature trend over time. The visualization is built with the Vega-Lite API, which handles the mark encoding through `vl.markLine` and the x-axis as temporal data, while the y-axis encodes the temperature values. Data is fetched from a CSV file via `d3.csv` and rendered as an SVG using the Vega renderer, with a custom tooltip from `vega-tooltip` for interactive inspection of temperature values. The chart automatically fits the viewport size, and the `config.js` file adjusts axis and label styling for improved readability.