PMM Inventory: Long lists unclear; poor contrast & column headings scroll out of view

When we have a huge list of instances added, PMM-Inventory is not that friendly, we also have an issue with the color of the inventory table and the container background color, both black create confusing contrast and it is not obvious for the user to know if we have a scroll or not. 

See the gif attached with the ticket. 

Suggestion: 

1) Could we please add a better UI to let users know they can scroll through the Agents list (currently very confusing)
2) Could we make the table header and tabs stick on the top, so when we scroll down, we know which Tab we are in and what are the column headers. (maybe obvious for some users but not for all)