Hi
You can use this CSS in your custom.css file
body .sppb-btn.sppb-btn-default:after, body .sppb-btn.sppb-btn-primary:after, body .sppb-btn.btn-primary:after, body .btn.sppb-btn-default:after, body .btn.sppb-btn-primary:after, body .btn.btn-primary:after{
background: #627be6 !important;
}
body .sppb-btn.sppb-btn-default:hover, body .sppb-btn.sppb-btn-default:focus, body .sppb-btn.sppb-btn-default:active, 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-default:hover, body .btn.sppb-btn-default:focus, body .btn.sppb-btn-default: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{
border-color: #627be6 !important;
}