Hi

Use this custom CSS in your custom.css file

body .sppb-btn.sppb-btn-primary:hover, body .sppb-btn.sppb-btn-primary:focus, body .sppb-btn.sppb-btn-primary:active, body .sppb-btn.btn-primary:hover, body .sppb-btn.btn-primary:focus, body .sppb-btn.btn-primary:active, body .btn.sppb-btn-primary:hover, body .btn.sppb-btn-primary:focus, body .btn.sppb-btn-primary:active, body .btn.btn-primary:hover, body .btn.btn-primary:focus, body .btn.btn-primary:active{
      background-color: #81C41C !important;

}

.latest-trends-style .sppb-addon-image-layout-image:after{
  border-color: #81C41C !important;
}