Universal button custom styling

Hi Kriesi,

Just wanted to add some universal styles to all buttons in our site (sliderbuttons, general content buttons etc.)
I wish to have two looks. A light and a dark.

I’m trying to follow: https://kriesi.at/documentation/enfold/button/#toggle-id-12
But can’t find the “custom CSS class name support” under “layout builder”, and can’t find a topic in here that enlightens me…

Can you help?
Right now i’m designing each botton style like this, which seems not be be a good idea:
.avia-button {
font-size: 0.8em !important;
text-transform: uppercase;
color: #ffffff !important;
padding-left: 1.4em !important;
padding-right: 1.4em !important;
padding-top: 1em !important;
padding-bottom: 1em !important;
font-weight: 400 !important;
letter-spacing: 0.3em;
background-color: #232323 !important;
border: 1px solid #232323 !important;
border-radius: 0px !important;
}
.avia-slideshow-button {
font-size: 0.8em !important;
color: #232323 !important;
padding-left: 1.4em !important;
padding-right: 1.4em !important;
padding-top: 1em !important;
padding-bottom: 1em !important;
font-weight: 400 !important;
letter-spacing: 0.3em;
background-color: #fff !important;
border: 1px solid #fff !important;
border-radius: 0px !important;
}
.avia-slideshow-button:hover {
padding-left: 1.4em !important;
padding-right: 1.4em !important;
padding-top: 1em !important;
padding-bottom: 1em !important;
opacity: 1 !important;
font-size: 0.8em !important;
color: #77855a !important;
font-weight: 400 !important;
letter-spacing: 0.3em;
background-color: #fff !important;
border: 1px solid #fff !important;
border-radius: 0px !important;
}