static.css not updating

Hi guys, quite new to the web development scene, scratching my head with this one.

The primary navigation menu wasnt too visible on the clients site (http://nlaproduction.com/) so using chrome inspect and by using the style window on the right I managed to add a transparent background to the menu then updating the static.css file in the theme folder accordingly… I was happy to see the change took effect, then I wanted to make further changes so I went back to static.css and made further edits but the changes now do not take effect 🙁 Then I tried to restore the default original style.css and even though it updates on the ftp server the website still loads the one that I updated once, chrome inspect also shows differently to what actually exists on the FTP server. Any ideas why this could be happening?