How to fix header-pic relative high 100%

Not sure about the settings of the image or associated CSS rule(s). But you can give height: auto; for the header image a try.

In wordpress-theme cerauno I can not find a possibility of html-input for header-pic.

There is only a recommended size for header-pic of 1400 x 200 px

And there are several php editors. But I do not have any php knowledge.

There is an input field for additional CSS. Here, an input of a correcting command would be possible, I think

Hi @harrykoi

The header image on Cerauno is designed as more of a background, with text based title, or a logo, on top of it. That would give the title more height, so it could work better on larger screens.

So – you could try uploading a copy of your header without the text in it, and use a normal text title. Or you could make sure the Jetpack plugin is installed which enables Cerauno’s Logo feature.

Then under your Customizer, you’ll see a Site Title, Tag Line, and Logo option. You can add an image based logo that way.

Lastly, you could try a CSS based solution, forcing the header to a taller height.

Under the Additional CSS section in the Customizer, try this snippet:

@media screen and ( min-width: 1280px) {
    .site-branding {
        min-height: 200px;
    }
}

That will leave small and medium screens alone, but make a taller header on large screens.