How to center the content on the page?

Question

css

It is necessary to align the Iframe (refers to the Yandex.money payment form). I've tried everything I know... text-align in CSS, align on the element itself, made the element block, added and ? uselessly.

<iframe src="https://clck.ru/GMH5t" 
             width="100%" height="222" 
             frameborder="0" 
             allowtransparency="true" 
             scrolling="no">
</iframe>

Answer 1

https://codepen.io/anon/pen/wbbvVM