Sometimes, when we're coding and we try to set the height using a percentage, it doesn't work as we expect it to. So, in this solution, we will know why this happens and will learn how to set the height so that we can give the full height of any element.
Let's dive in!
When you set the height or width of an element as a percentage, it's calculated based on its parent's size. Usually, block elements expand to fill their parent's width, which goes all the way to the <html> element. So, the width of a block element isn't affected by its content.
When you set an element's height in percentage, it can still change unexpectedly. This occurs because the parent element already has a specified height. This mistake often happens in larger projects where developers forget to set the parent element's height correctly.
To resolve this issue effectively, ensure that you define the height of the parent element using units such as vh or px before assigning the child element's height in percentage. This is because vh units represent viewport height, while percentage units are based on the parent element's height. Understanding this difference is key to addressing the problem successfully.
In this example, we didn't set the height of the parent element (body) for the child element. Therefore, only the height specified in pixels is working, while the height specified in percentage is not working as expected.
<head>
<title>Document</title>
<style>
.parent {
width: 50%;
height: 200px;
background: steelblue;
}
.child {
width: 50%;
height: 50%;
background: thistle;
}
</style>
</head>
<body>
<div class="parent"></div>
<hr>
<div class="child"></div>
</body>
The height of a child element is affected by its parent element. Once you set the parent element's height, you can use percentages to set the child element's height. For instance, if the parent's height is 50vh and the child's height is 50%, the child's height will be half of the parent's height.
As you can see in the below example, you'll notice that even though we've set the child element's height in percentage, it still takes up space. This happens because we've also defined the parent element's height using viewport height units (vh).
<head>
<style>
body {
height: 50vh;
background-color: thistle;
}
.height-working {
height: 50%;
background: steelblue;
width: 50%;
}
</style>
</head>
<body>
<div class="height-working"></div>
</body>
The height of a block element depends on its content. Without a specific height set, it adjusts to fit its content, expanding as needed.
Avoid assigning a height to the parent element in percentage units when there's no content, as it becomes meaningless for the calculation.
Just remember, if you want to set the height using a percentage unit, make sure you first set the height of its parent element using the vh unit.
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