Most of the work is in document segmentation:
https://arxiv.org/abs/1704.01474
https://arxiv.org/abs/1711.07695
https://arxiv.org/abs/1710.07363
I'm pretty sure I've seen some webpage work too, but I don't have the reference.
Those are all about segmenting the text on a page from the background, and not semantic segmentation, which I thought you were talking about ("segment the page and decide what is the navigation").
Finding the text in a screenshot of a webpage should be easier than doing it for handwritten documents; it's the "decide what is the navigation" part that I'm doubtful about.
I expect that to be significantly different from the task of segmenting objects in a photo, because most of the boundaries are not revealed by texture differences, but implicit in the arrangement.