If You want to use condition formatting in Text Box or wanna change the background/font-color based on different selection then i think it may help you.
Here i put a dimension filter and a text box.
based on dimension filter selection i want to change the background color of the text box.
for achieving that things i used a Custom CSS file…..
saved that file in my root folder.
then i write some script in dimension filter event “On Apply”……..
so using that script that thing work.