polyvision

Hello @socialdzine,

this worked for me:

Child theme header:

<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">

Child theme style.css:

@media screen and (max-width: 1280px) {
    .has-header-image .custom-header-media img,
    .has-header-video .custom-header-media video,
    .has-header-video .custom-header-media iframe,
    .has-header-image:not(.twentyseventeen-front-page):not(.home) .custom-header-media img {
        height: auto;
        left: 0;
        max-width: 100%;
        min-height: 0;
        -o-object-fit: unset;
        object-fit: unset;
        position: relative;
        -ms-transform: none;
        -moz-transform: none;
        -webkit-transform: none;
        transform: none;
    }
}

@media screen and (max-width: 1024px) {
    .has-header-image .custom-header-media img,
    .has-header-video .custom-header-media video,
    .has-header-video .custom-header-media iframe,
    .has-header-image:not(.twentyseventeen-front-page):not(.home) .custom-header-media img {
        height: auto;
        left: 0;
        max-width: 100%;
        min-height: 0;
        -o-object-fit: unset;
        object-fit: unset;
        position: relative;
        -ms-transform: none;
        -moz-transform: none;
        -webkit-transform: none;
        transform: none;
    }
}

@media screen and (max-width: 768px) {
    .has-header-image .custom-header-media img,
    .has-header-video .custom-header-media video,
    .has-header-video .custom-header-media iframe,
    .has-header-image:not(.twentyseventeen-front-page):not(.home) .custom-header-media img {
        height: auto;
        left: 0;
        max-width: 100%;
        min-height: 0;
        -o-object-fit: unset;
        object-fit: unset;
        position: relative;
        -ms-transform: none;
        -moz-transform: none;
        -webkit-transform: none;
        transform: none;
    }
}

@media screen and (max-width: 480px) {
    .has-header-image .custom-header-media img,
    .has-header-video .custom-header-media video,
    .has-header-video .custom-header-media iframe,
    .has-header-image:not(.twentyseventeen-front-page):not(.home) .custom-header-media img {
        height: auto;
        left: 0;
        max-width: 100%;
        min-height: 0;
        -o-object-fit: unset;
        object-fit: unset;
        position: relative;
        -ms-transform: none;
        -moz-transform: none;
        -webkit-transform: none;
        transform: none;
    }
}

Looks clumsy but works.
Michael