This example visualizes EEG arousal and valence data over time as a thick, gradient-colored line chart against a dark background. It plots the F4 frequency values from the provided CSV files for each epoch, using a blue-to-red gradient to indicate signal intensity. The visualization is built with D3.js, employing linear scales, SVG axes, and a line generator, with small circles marking each data point that reveal frequency details on click. The black canvas and exaggerated chart dimensions emphasize the waveform's shape and peaks.