How can I make Flexbox children 100% height of their parent?

Making Flexbox Children 100% Height of Their Parent: Simple Solutions 📏👶

So, you're trying to fill the vertical space of a flex item inside a Flexbox, but the children don't seem to be cooperating? Don't worry, you're not alone! Many developers have faced this common issue. In this blog post, we'll explore different solutions and provide easy, working examples to help you achieve your desired layout.

The Problem: Children Don't Fill the Required Height 😱

Let's take a look at the code snippet that sparked this question:

<div class="container">
  <div class="flex-1"></div>
  <div class="flex-2">
    <div class="flex-2-child"></div>
  </div>
</div>

The .container is a Flexbox with a height of 200 pixels and a width of 500 pixels. Inside it, we have two flex items: .flex-1 and .flex-2. The issue arises when we try to make .flex-2-child fill the full height of .flex-2.

Easy Solutions 👍🔧

Solution 1: Use Flexbox's align-items Property

One simple way to make the children 100% height is to use the align-items property on the parent flex container. Here's what the modified CSS would look like:

.container {
  height: 200px;
  width: 500px;
  display: flex;
  flex-direction: row;
  align-items: stretch; /* Add this line */
}

By setting align-items to stretch, all flex items inside .container will be stretched vertically to match the height of the tallest flex item. This property works well in modern browsers.

Solution 2: Utilize the flex-shrink Property

Another approach is to use the flex-shrink property on the children. This solution assumes that the flex item you want to fill the height of has a fixed height or a percentage-based height. For example, if you want .flex-2 to have a fixed height of 100%, you can modify the CSS as follows:

.flex-2 {
  position: relative;
  flex: 1;
  background-color: red;
  display: flex;
  flex-direction: column; /* Add this line */
}

.flex-2-child {
  flex-shrink: 0; /* Add this line */
  background-color: green;
}

By setting flex-direction to column on .flex-2 and applying flex-shrink: 0 to .flex-2-child, you prevent the child from shrinking and ensure it fills the available vertical space.

It's Not Perfect Yet... 🤔

Unfortunately, the above solutions may not always work as expected in all browsers. Currently, there are known incompatibilities in Chrome and Firefox. But, fear not! There's still hope.

The Workarounds 🛠️

Workaround 1: Set the Flex Container Height to 100%

To address the compatibility issues, you can explicitly set the height of the flex container to 100%. Here's how the CSS would look:

.container {
  height: 200px;
  width: 500px;
  display: flex;
  flex-direction: row;
  height: 100%; /* Add this line */
}

While it may seem weird because flex items already have a default height of 100%, explicitly setting the container's height often resolves the problem in Chrome.

Workaround 2: Use Absolute Positioning for the Child

If the previous workarounds still don't do the trick, you can resort to using absolute positioning for the child element. Modify the CSS for .flex-2-child as follows:

.flex-2-child {
  position: absolute; /* Add this line */
  height: 100%;
  width: 100%;
  background-color: green;
}

By positioning the child absolutely, it will fill the entire height and width of its parent. However, keep in mind that this solution can have its own challenges, so use it sparingly and only if other alternatives fail.

Conclusion: Experiment and Find Your Perfect Fit! 💡🧩

Although making Flexbox children 100% height of their parent can be tricky, we've explored several solutions and workarounds that should work in most cases. Remember to experiment with different approaches and see which one suits your specific needs.

Now it's your turn! Dig into your CSS code, try out these solutions, and don't hesitate to share your experiences and success stories. Leave a comment below and let's conquer the mysterious world of Flexbox together! 😊💪

Click here to try out the code on JSFiddle