Header logo size on mobile

Hi, I’m having trouble with my header logo not being responsive on mobile at https://www.quitegoodadventures.co.nz. I’ve read other forum posts and tried adding the below css as per another support post, but it’s not working. Anything else I can try?

@media only screen and (max-width: 767px){
.custom-logo{
max-width: 300px;
}
}