Hello,

Please add this code to the Theme Settings > Custom CSS > Global:

body .whb-with-shadow {
    -webkit-box-shadow: 0 1px 8px rgba(0,0,0,.7);
    box-shadow: 0 1px 8px rgba(0,0,0,.7);
}

Increase or decrease the value .7 in each line as per your needs. Initially, it was .1

Best Regards