You may need to disable the file compression settings temporarily after adding the css.

This did the trick – thanks a lot!

Hey Ismael,

when I use the Google dev tools the approach works. But when I insert the CSS into our style.css nothing happens.
It seems to be overridden completely.
This is what I find in dev tools for the iframe-scaler:

.mfp-iframe-scaler iframe {
    position: absolute;
    display: block;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    box-shadow: 0 0 8px rgb(0 0 0 / 60%);
    background: #000;
}

Hi,

I used your suggestions @Guenni007 and those fixed it. Thank you!

Best Regards
Leonie