Target Simple List Button

here is code for the button 

.list-item a.sqs-button-element--primary {
  letter-spacing: 0em !important;
}

.list-item a.sqs-button-element--primary:hover {
  /* notice the 0.5 in the last argument in the hsla, thats alpha, 0.5 means 50% transparent. */
  background-color: hsla(289.41,92.73%,10.78%,0.5) !important;
}

This will update the hover color also.