CSS to adjust log size

Hi guys, I’m trying to reduce the size of the logo displayed on both the listings page and the details

I presume CSS would be the logical way to do this, I certainly can’t find a way within GD otherwise

For the details page the relevant CSS file appears to be _elements.scss img {
max-width: 100%;
}
However of course it’s not normally a good to edit the original as it would be overwritten on plugin upgrade, so I would expect to put the CSS into the additional CSS panel in Appearance.

However I cannot find the correct code to use

So A – Am I going about this the right way, if so some guidance please. Or B – I’m being a fool and missing the really obvious way to accomplish this the easy way

Thanks!