Okay if you do not know that then you have not done any CSS editing so just forget about that for now.
What you did was use the theme customizer on Bold Life and then chnage to Academica.
Will you please try these troubleshooting tips so we can see if we can get Bold Life back for you without you waiting for Staff help? (It's the weekend and Staff help will probably be days away.)
If you are not running one of the browsers and versions listed at http://browsehappy.com/ please try upgrading or switching first.
Note: If you are using an IE9 browser in compatibility mode that makes it render as IE7 and IE7 is not supported. To disable see > http://www.sevenforums.com/tutorials/1196-internet-explorer-compatibility-view-turn-off.html
If you are running one of the browsers and versions listed at http://browsehappy.com please do these four things:
1. Try clearing your browser’s cache:
2. Make sure that you have third-party cookies enabled: http://en.support.wordpress.com/third-party-cookies/
3. Try with all browser extensions or add-ons temporarily disabled.
4. Try enabling HTTPS: http://en.support.wordpress.com/https/
If it’s still happening, let us know which browser (and version of it) you’re using by checking here if necessary http://www.whatbrowser.org/ and also post any error reports you get.