Class on button doesn't work

Hello guys,

I try to give a class to my previous button but nothing work.

This is my code :
[previous class:wpcf7-submit “PRÉCÉDENT”]

Before the last fix, this code worked. But now nothing.

If you can help me that will be perfect 🙂

(sorry for the language, I’m french)

https://ww.wp.xz.cn/plugins/contact-form-7-multi-step-module/