@flaky-gpu-87733 nvm I was able to find it also. Pretty easy, just add !important after your z-index value you want to set :
.bp-widget-web {
border: none;
display: block;
position: fixed;
visibility: none;
z-index: 9999!important;
max-height: 100vh;
max-width: 100vw;
transition: none;
background: none transparent;
opacity: 1;
font-size: 16px;
letter-spacing: 0;
-webkit-font-smoothing: antialiased;
padding: 0;
color-scheme: none;
}