First off, you need a better forum for suggestions that allows images or attachments. This one is hard to demonstrate otherwise.

I am terribly disappointed with the lack of progress in layout rendering for the UI in the web client (and probably other clients). This should be an area that has a core team assigned on an ongoing basis to constantly be improving UI functionality/capabilities for each release...but I digress.

Specifically for this "idea", the basics of page rendering need to be looked at. I have a very simple custom page I developed (Card type) that has a few fields on the page, and then a part to show an HTML view. The rendering is a massive disappointment. I want the subpage/part to expand to use the available real estate. Instead, it renders as shown at the link below. A large amount of completely wasted space at the bottom. So frustrating. Please give this the attention it deserves/needs.

https://portal.epimatic.com/images/poor_layout.png