Make absolute positioned div expand parent div height

Enter Flexbox and Grid systems

While our JavaScript friend here is pretty good at adjusting the height dynamically, flexbox or grid layout are more advanced CSS strategies for managing layouts. The advantage is that they don't require specific height declaration and are widely supported in most browsers.

Harnessing smart CSS

By setting align-items and adjusting flex-direction, you can reverse the visual order of elements without altering the HTML structure. This way, you cater to responsive designs effortlessly. For instance, a flex container can rearrange its kids in a column-reverse fashion on mobile screens, because well, change is good!

@media only screen and (max-width: 768px) {  // Media queries to the rescue!
  .flex-container {
    display: flex;  // flex me baby!
    flex-direction: column-reverse;  // The divs are doing the limbo
  }
}
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Overflow management trick

Content that's eager to overflow its boundaries? Simply set overflow: hidden on children divs. It helps maintain the visual appeal while managing the containment of child elements. It's like hiding the mess under the rug, but way more professional!

Leaning on media queries

Media queries are your magic flex buddy for varying screen sizes. A little adjustment to the flex properties can make a huge difference to dynamic content reordering without cranking up JavaScript.

Utilizing CSS properties to the fullest

Embracing height: 100%

When absolute positioning is unavoidable, ensure child divs get height: 100%. By doing so, they expand in harmony with the parent container. But remember, this only works if the parent has a defined height.

The Clarification of Floats

Clearing floats with the clearfix method could be the answer to wrap its floated children:

.clearfix::after {
  content: "";
  display: table;  // What's on the menu today? Oh, just some clearfix
  clear: both;  // Gone with the wind
}

.parent {
  display: block; // Blocks are cool, aren't they?
}
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Position-ception: Swap places with position

In unique scenarios, try swapping positions. That is, apply absolute positioning to the parent and relative positioning to children. It's all about thinking out of the box!