custom css not working

I just noticed that the custom css isn’t working anymore to increase the font size on the large button.

The site is https://www.onlineflamencostudio.com
I’m looking at the “join now” buttons on that page.

The css that I have is:

.vc_btn3.vc_btn3-size-lg {
font-size: 28px;
}

Thank you very much for your help.