CSS: Footer overlapping content, other glitches

Question

I've looked around for similar issues here and in other places, but I can't seem to find a definitive answer. When I add enough text to a page that it would get to the footer, the footer simply overlaps the text. Same thing if I reduce the size of the browser window to force the footer and the container that holds the content to meet. Occasionally, this also manifests in the "container" aka the lighter gray part, shrinking for some reason, even though it should always be taking up 100% of the height.

This is the sort of stuff that keeps me up all night, so I'm not thinking very clearly. I'm sure it's something stupid and easy to fix, but I'm not a professional designer and am certainly missing what the issue is.

Below is my CSS, and a JSFiddle that I made with all the relevant parts of a page.

html, body {
    margin: 0;
    padding: 0;
}

html, body {
    background: #252525; 
    font-family: Arial, Helvetica, sans-serif;
    height: 100%;
    text-align: center;
}

body {
    background: #363636;
    border-left: 1px solid #111;
    border-right: 1px solid #111;
    margin: 0 22.5%;
}

#container {
  color: white;
  margin-bottom: 2em;
  min-height: 100%;
  overflow: auto;
  padding: 0 2em;
  text-align: justify;
}

#footer {
  bottom: 0;
  color: #707070;
  height: 2em;
  left: 0;
  position: fixed;
  font-size: small;
  width:100%;
}

A mockup of a typical page.

Answer 1

Change this:

#footer {
    bottom: 0;
    color: #707070;
    height: 2em;
    left: 0;
    position: relative; //changed to relative from fixed also works if position is not there
    font-size: small;
    width:100%;
}

Demo