CSS: auto height on containing div, 100% height on background div inside containing div

Question

The problem, is that I have a content div which stretches its container height-wise (container and content div have auto height).

I want the background container,

Answer 1

Make #container to display:inline-block

#container {
  height: auto;
  width: 100%;
  display: inline-block;
}

#content {
  height: auto;
  width: 500px;
  margin-left: auto;
  margin-right: auto;
}

#backgroundContainer {
  height: 200px; /*200px is example, change to what you want*/
  width: 100%;
}

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