Changing the hover color of a link

Yes it is.

Under themes, choose Assets.
Choose “dashboard.html” from the drop down.
Got to line 40 with has this block :

.sidebar-elt>.content a:hover {
background: #444;
}

and change that colour to whatever you want (this is the link background colour).

Then go to line 53 and edit this block :

.sidebar-elt a:hover, .sidebar-elt a:active {
    color: white;
 }

and change this colour for the text.