No scrollbar in private messaging inbox + formatting question

Hi,
1- The scrollbar of the private messaging inbox (and probably the other folders) does not exist, check the photo please:

https://www.dropbox.com/s/psonu0qiq82to9b/scrollbar.png?dl=0

2- I have two formatting questions:
a. How can I remove the avatar that appears next to the name of senders?
b. How can I change the blue color which appears when I press on a certain inbox message? please check this photo: https://www.dropbox.com/s/zoavdkwoplhcy0d/css.png?dl=0

thanks in advance