This example draws a line graph of weekly temperature readings for San Francisco. It uses the Vega-Lite API to define a single line mark with a time-encoded x-axis and a quantitative y-axis, with tooltips showing temperature values. The visualization renders as SVG via Vega and Vega-Lite, while D3’s `csv` function loads the data from a GitHub gist. The code customizes label styling for readability and fits the chart to the full browser window.