Customising Font on Newsletter/Signup Form Button

Site URL: https://www.riverrituals.com.au

Hey there, hoping someone can help here. I have managed to customise heading fonts, body paragraph fonts & most button fonts - though having trouble just with the newsletter button here. Wanting to change the font to 'Copperplate' but am struggling to find the right code for newsletter/signup form. So far my coding has worked fine for individual buttons & image block buttons...

codes displayed in just lines of css under // newsletter button // haven't worked at all

Help will be much appreciated! 

Thanks,

Use this CSS

form.newsletter-form * {
    font-family: 'Raleway-Regular' !important;
}

Thanks so much! That worked a treat!