Editing the Elgg topbar


I am using Elgg 1.8.18, Version - 2014110100  , and I just wants to edit the height of topbar , but when I look the css file location through Google Chrome Inspect element that show this directory [ /cache/css/default/elgg.1395202524.css ] , but there no such type of directory in my server , can you help me to fix this one, 

Thanks in advacne .