why the content of iframe is zoom out and zoom in during the resizing of the webpage?

in my webpage, formally the ads are showing and the ads are setted up the code by a iframe and also I tried once a inspect and then resizing the webpage and that is maximize and minimize the webpage(and that is inspect webpage move resize up and resizing down)., my whole webpage is changing their aspect ratio of their suitable maximize and minization of the webpage. And the ads are only showing abnormal during the resizing (like zoom in during resizing up and zoom out during resizing down).(ads are in a iframe of a html code).

i try a meta tag and media queries and not I had a exact correction.