problem with iframe witdth

While making a site, I came across a problem and I hope you can help me. It's probably something very easy, that I don't know about.

The problem is, I am making a website with a menu on the left with links that load in the iframe on the right. the left menu has to be 215 pixels, and the right frame has to be the rest of the screen.

For some weird reason, this iframe only want's to be 300 pixels, so if I want to load a page that is more, it stays at 300 pixels.

The site is here, click for example on "makke开发者_如何转开发lijke levels", the error message from 000webhost should be the entire right part of the screen but just stays at 300 pixels.

Thanks in advance, Friso

Is this correct CSS?

right_iframe {
position: absolute;
left: 216px;
width: auto;
height: 100%;
float: right;
margin: 0px;
border: 0px;
}

Shouldn't you change the width from to 300 px?

width:auto isnt working because you need to specify the right position too. this should work, although i havent tested it:

.right_iframe {
  position:absolute;
  left:216px;
  right: 0px;
  width: auto;
  height: 100%;
  margin:0px;
  border: 0px;
}