Css problem

Hi,
I don’t know why I can’t set in green the text “CHIAMA SUBITO” in http://www.poliedra.it/Nuovo/clienti-e-partner/
I set a Extra class name “testoverde” in the column and in the Top icon box setting and the code
.testoverde{
color:#48AD0A;
}
in the tab custom CSS in the theme options but it does’t work!

It’s not the unique issue with the css because I can’t center a button in a row!
Thank you!