html - Position Absolute + Scrolling

Question

With the following HTML and CSS

.container {
  position: relative;
  border: solid 1px red;
  height: 256px;
  width: 256px;
  overflow: auto;
}
.full-height {
  position: absolute;
  top: 0;
  left: 0;
  right: 128px;
  bottom: 0;
  background: blue;
}

<div class="container">
  <div class="full-height">
  </div>
</div>

Answer 1

You need to wrap the text in a div element and include the absolutely positioned element inside of it.

<div class="container">
    <div class="inner">
        <div class="full-height"></div>
        [Your text here]
    </div>
</div>

Css:

.inner: { position: relative; height: auto; }
.full-height: { height: 100%; }

Setting the inner div's position to relative makes the absolutely position elements inside of it base their position and height on it rather than on the .container div, which has a fixed height. Without the inner, relatively positioned div, the .full-height div will always calculate its dimensions and position based on .container.

* {
  box-sizing: border-box;
}

.container {
  position: relative;
  border: solid 1px red;
  height: 256px;
  width: 256px;
  overflow: auto;
  float: left;
  margin-right: 16px;
}

.inner {
  position: relative;
  height: auto;
}

.full-height {
  position: absolute;
  top: 0;
  left: 0;
  right: 128px;
  bottom: 0;
  height: 100%;
  background: blue;
}

<div class="container">
  <div class="full-height">
  </div>
</div>

<div class="container">
  <div class="inner">
    <div class="full-height">
    </div>

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  </div>
</div>