Header

Link to site would help.

https://new.volleybal-dedemsvaart.nl/

1) To find the right size, experiment with:

.tc-header .brand .site-logo img {
    width: 30%; /* Adjust */
}

2) There are some extra selectors you can add, for example:
.sticky-disabled
.sticky-enabled
.home
.page-id-33 (Heren 1)

So you’d end up with something like:

.home .sticky-disabled .tc-header .brand .site-logo img {
    width: 100%; /* Adjust */
}
.sticky-enabled .tc-header .brand .site-logo img {
    width: 30%; /* Adjust */
}

Nice, thanks.
I think this is what i′m looking for.