Backend Css Template For Product Block Vendor

i need to add thi code of css for backend vendor panel mobile usage, with this code is easy to manage product because i shoe them in a slide mode.
but where do i add it ?? i cant find it maybe i'm to drunk :grin:
@media only screen and (max-width: 480px) {
.table-responsive tbody {
display: flex;
overflow: auto;
.table-responsive tbody tr {
flex: 1;
padding: 1em;
border: solid;
Thank you


Please check