Full implementation of WaveSurver Spectrogram

Hi, I'm attempting to implement a spectrogram visualization for an audio classification/transcription task. I'm trying to base my solution on this post, but am having no luck. I've tried the modification to the global_css value mentioned in the post as well as various other things, but nothing is working.

The post is also a little vague, e.g. "with something like", incomplete (no HTML included) making it difficult to implement (for a front end noob like myself anyway!)

Does anyone have a complete working example of wavesurfer integration with a audio interface?