How Can I Set CSS Margin or Padding as a Percentage of the Parent Container's Height?

Setting Margin or Padding as a Percentage of Parent Container Height in CSS

When aligning elements vertically using CSS, it is often desirable to set the padding or margin as a percentage of the parent container's height. However, setting padding-top, for example, using a percentage value calculates that percentage based on the container's width, causing the vertical alignment to snap when the container's width changes.

To overcome this limitation and align elements vertically as a percentage of the parent container's height, consider the following approach:

Instead of setting padding or margin directly on the child element, create a nested structure with an additional inner div:

<div>
<p>Style the inner div using top or bottom for vertical padding or margin, and set its position to relative or absolute to allow for precise placement:</p>
<pre class="brush:php;toolbar:false">.inner-container {
  top: 50%; /* Vertical padding or margin equal to 50% of parent container height */
  position: relative;
}

By using the top or bottom properties, you can set vertical padding or margin as a percentage of the container's height, ensuring that the alignment remains consistent regardless of the container's width.