Opera Mobile ignores overflow: hidden | Strange white offset beyond the page content

Question

It's some kind of magic, really. I didn't see anything similar before. So only on Opera Mobile (the latest ver) on the Android device (any), I get a strange white offset while some of the nodes cross the body content width (i.e. became beyond the visible layout). Of course, I don't need any such content, as well as such a white offset.

So I tried to set overflow: hidden as a solution on the parent node(body). Unfortunately, it exactly doesn't work with Opera Mobile (again, the white offset around the page became visible and scrollable).

Exampe of the real code:

#parent_body {
    overflow-x: hidden;
    overflow-y: scroll;
    position: relative;
}

#child_tooltip {
    z-index: 99999;
    display: table;
}

#tooltip_content {
    position: absolute;
    z-index: 50;
    left: 430px;
    top: 175px;
}

Does anyone face such an issue previously? I'll appreciate a lot any help!

Thanks in advance.

Example of such "white offset" around the page: