To add a gradient to all tertiary buttons, you can use this code to Custom CSS box.
If code doesn’t work, you can comment below, message or email me.
a.sqs-button-element--tertiary {
background: linear-gradient(360deg, #ea8038, #e56a34) !important;
background: -webkit-linear-gradient(360deg, #ea8038, #e56a34) !important;
-webkit-transition:all 0.3s ease-in-out!important;
-o-transition:all 0.3s ease-in-out !important;
transition:all 0.3s ease-in-out !important;
}
Result