Edu-Clean Theme. how can i make avatars smaller on Activity page?

Hello, on the Activitiy page, can i make the avatars display smaller? i would like them to be the same size they are on the members page.

Ive been messing around with the css files but
I assumed this was it:
#activity-stream .activity-avatar {
margin: 0px 15px 0px 0px;
padding: 0px;
float: left;

but when i add a width & height, the avatar stays the same size, but the alignment gets messed up.
Does anyone know how I could make the activity page avatars smallers? thanks