What is the key difference between using `height: 100%` and `min-height: 100%` in CSS?

height:100% vs min-height:100%

In CSS, setting the height of an element can be achieved using various properties, including height and min-height. While both properties control the height of an element, they have distinct effects and priorities. Understanding their differences is crucial for effectively controlling the layout and functionality of web pages.

Key Difference

The primary difference between height:100% and min-height:100% lies in their application and impact on the element's size.

• height:100%: Sets the element's height to be equal to the height of its containing block. It dynamically adjusts to any changes in the parent container's size. However, it can be overridden by other properties like max-height.
• min-height:100%: Ensures that the element's height is at least 100% of its containing block. This property acts as a lower bound, preventing the element from shrinking below the specified value. Even if a lower explicit height is set, min-height:100% overrides it.

When to Use height:100%

• To create elements that automatically stretch to fill their containing block vertically.
• For elements that need to adjust their height to match the size of their content, such as dynamic text blocks or image containers.

When to Use min-height:100%

• To ensure that elements maintain a minimum height, even if their content is insufficient or the container size is reduced.
• For elements that need a fixed minimum height to preserve important content or functionality, such as navigation menus or form inputs.

Example

Consider the following HTML code:

<code class="html"><div id="container">
  <p>This is a paragraph.</p>
</div></code>

CSS using height:100%:

<code class="css">#container {
  height: 100%;  /* Stretches the container to match the full height of its parent */
}</code>

This CSS will make the container's height equal to the height of its parent element, creating a dynamic layout that adjusts to changes in the parent's size. The paragraph will occupy the full available height within the container.

CSS using min-height:100%:

<code class="css">#container {
  min-height: 100%;  /* Ensures the container is at least 100% of its parent's height */
}</code>

In this case, the container will have a minimum height of 100% of its parent's height. The paragraph will only occupy the space required by its content, and the container will fill any remaining space up to its minimum height.

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