CSS fills the screen

In web development, especially responsive design, a common problem is how to make an element fill the entire screen. Sometimes we want an element to take up the entire width or height of the screen, creating a full-screen effect. This article will discuss how to achieve this using CSS.

Making an element take up the entire width of the screen

Method 1: Using width: 100%

The simplest method is to set the element’s width to 100%, making it take up the entire width of the screen. We can add the following CSS style to the element:

.full-width {
width: 100%; 
}

Then use this class name in your HTML:

<div class="full-width">This element will take up the full width of the screen</div>

This way, the element will take up the entire width of the screen, regardless of the screen size.

Method 2: Using vw Units

In addition to directly setting the width to 100%, we can also use the vw (viewport width) unit to make an element take up the entire width of the screen. 1 vw is equal to 1% of the viewport width, so 100 vw is equal to the entire viewport width.

.full-width {
width: 100vw; 
}

This also makes the element take up the entire width of the screen.

Method 3: Using the calc() Function

Sometimes we might want an element’s width to be slightly smaller or larger than the viewport. We can use the calc() function to achieve this. For example, if we want the element’s width to be 20 pixels less than the viewport width:

.full-width {
width: calc(100vw - 20px); 
}

This will create the effect of the element taking up the entire width of the screen minus 20 pixels.

Make the element take up the full height of the screen

Method 1: Use height: 100%

We can also make an element take up the entire height of the screen by setting its height to 100%. We can add the following CSS style to the element:

.full-height {
height: 100%;
}

Then use this class name in your HTML:

<div class="full-height">This element will take up the entire height of the screen</div>

Method 2: Using the vh Unit

Similar to the vw unit, we can also use the vh (viewport height) unit to make an element take up the entire height of the screen. 1vh equals 1% of the viewport height, so 100vh equals the entire viewport height.

.full-height {
height: 100vh; 
}

This will make the element take up the entire height of the screen.

Method 3: Using the calc() Function

Similarly, we can use the calc() function to control the height of an element to achieve special effects. For example, if we want the height of an element to be 50 pixels less than the viewport height:

.full-height {
height: calc(100vh - 50px); 
}

This will make the element take up the entire height of the screen minus 50 pixels.

Combined Application

Using the above methods, we can easily make an element occupy the entire width or height of the screen, or both. Here’s an example of how to use it:

<!DOCTYPE html> 
<html lang="en"> 
<head> 
<meta charset="UTF-8"> 
<meta name="viewport" content="width=device-width, initial-scale=1.0"> 
<title>Full Screen Example</title> 
<style> 
.full-screen { 
width: 100vw; 
height: 100vh; 
background-color: #f0f0f0; 
color: #333; 
display: flex; 
justify-content: center; 
align-items: center; 
font-size: 24px; 
} 
</style> 
</head> 
<body> 
<div class="full-screen">This element will take up the full screen width and height</div> 
</body> 
</html>

In this example, we use the vw and vh units to make the element take up the entire width and height of the screen and set some styles to enhance the display. This way, the element will take up the entire screen, regardless of the device the user accesses the page on.

In short, through the above methods and examples, we can easily use CSS to make an element occupy the entire width and height of the screen, achieving a full-screen display effect.