Wondering why there is no good document viewing technology for PCs

Reading research papers this past week has left me frustrated with document viewing on PCs. PDF is not the answer. It's good enough for storing documents that will eventually be printed, but it doesn't work well for reading on-screen.

I think you could essentially build what I want using HTML and CSS. My ideal solution would have the document expressed in HTML and then displayed using a CSS of my choosing. This would allow me to select comfortable fonts, colors, and text/image layout. What I think is needed is some sort of container format that would incorporate the HTML and image objects into something that can easily be downloaded, emailed and so forth.

Then, I could have a nice, light-weight document viewer that would essentially just apply my CSS settings to any document that I load, allowing for a pleasant reading experience customized to my tastes.