Make image fit full body

How can I make an image (NOT the background image) fit the whole screen?
Thank you.
P.S. Here what I mean, see the image , how do I stretch it to fit the same size as the background image.
or can I have 2 background images? I tried that but couldn’t set the opacity .

one way to do it (maybe not the best, i don’t know what it will do with more content) is to move the img out of the header element like this:

<img class="center"src="http://www.gsh.al/wp-content/forum/uploads/2018/02/Alien-abduction-607250.jpg" alt="aliens">
<title>
  Survey Form</title>
<header>
  <h1 id="title">Survey Form for Close Encounters of the Third Kind</h1></header>
  <p><b><i><u>Welcome to the X-files. Helps us gather information about<br>ALIENS!<hr><hr></p>
  <br><br><br>
</header>

and then in your css for the img, (i was looking at .center) add position: absolute;

hope that works out, otherwise we can find another way!

YES!!! It worked. :smile:
Why does the image have to be above the header. It doesn’t work if it’s below.
Thank you. :smile: :smile: