i just added a couple of minor tweaks (php code only) to my customizr child theme's function.php page, and created a new page template in my child theme, and now my edit css page is blank. the page won't load at all.
The URL I'm talking about is MYSITE/wp-admin/themes.php?page=editcss
i do have about 5-6 css customizations in there that are clearly working (at least they display properly on the site), and the functions in my child theme's functions.php are working fine.
i double-checked php and css bracket and curly brace closing and that all seems to be ok.