Exclude buttons from custom font with :not() propret not working

Site URL: https://gregorylassale.com

I am using a custom font injected in my cover page header but want to exclude buttons. I tried

<style>
/* Apply Custom Font to Entire Site Start */ 
@font-face {
	font-family: 'Montserrat Light';
	src: url('https://static1.squarespace.com/static/5aeb7d827e3c3a2bedb60363/t/608f5cfc8e8bd04a9e4e399b/1620008188969/Montserrat-Light.ttf');
}
/* target all elements except buttons */
*
:not(.sqs-slice-buttons-content) {
	font-family: 'Montserrat Light' !important;
}  
// --------------- End ---------------
</style>

but it's not working.  What is wrong in my code?

Thanks in advance.

Anyone?

You mean English, Francais buttons?

@tuanphan Yes. 

use this

<style>
  *:not(.sqs-slice-buttons a) {
    font-family: 'Montserrat Light' !important;
}
</style>