gmail showing blank screen code example

Example: gmail showing blank screen

I recommend fist checking in incognito mode to see if the same issue is 
occurring.

If you're able to log in just fine in incognito then it might be an extension
or you just need to simply clear your cache and cookies.
 
If you remove cookies, you'll be signed out of websites and your saved 
preferences could be deleted.

Also test using the Gmail Basic HTML Inbox.