Page size different HTML/CSS screens

Question

My doubt is in creating a page in html and css and that same page be opened on different screens.

For example, now I have a little problem.

HTML:

<iframe id="contentframe" width="300px" height="350px"  src="demo_iframe.htm" name="iframe_a"></iframe>

CSS:

#contentframe{
position: absolute;
left: 76.5%;
top: 130px;
}

If you open a page on a large screen, the margin is larger than a small screen. How can I fix this? I want the same margin to always appear regardless of the screen that opens the page.

Answer 1

Use this to control width and height and other properties:

iframe, object, embed {
        max-width: 100%;
        max-height: 100%;
}