Center Images using CSS

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Table of Contents:

Introduction
Prerequisites
Starter Code
Center Images Horizontally
Center Images Vertically
Center Images Both Horizontally and Vertically
Key Takeaways

Reading Time: 20 minutes | Coding Time: 30 minutes

Introduction

If you have used CSS (Cascading Style Sheets before) to develop a webpage, you know that if not like a standard programming language in that there are no runtime errors. If the logic in your code is not correct, there will simply be no changes on your webpage. This can lead to a lot of frustration and time spent browsing Google or Stack Overflow just to get the layout of our webpages to look how we want. In this OpenGenus article, I will go over the various ways to center images on a webpage using CSS, which can be one of the more tricky tasks when building a webpage. Centering images is important not only because it allows webpages to look more aesthetically pleasing, but also because the photos immediately draws the attention of the user and can improve readability on webpages with a lot of text.

Prerequisites

Familiarity with a text editor of your choice, such as VS Code
This article also assumes that you are familiar with basic HTML, and CSS selectors. It would also be a good idea to learn Flexbox before reading and following along with this article.

Starter Code and Images

We will be creating a webpage that displays some images.

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Centering Images Using CSS</title>
    <link rel="stylesheet" href="./styles.css" />
  </head>
  <body>
    <h1>Image Collection</h1>
    <img src="./colorado_1.jpg" />
    <img src="./colorado_2.jpg" />
    <img src="./london_1.jpg" />
    <img src="./london_2.jpg" />
  </body>
</html>

styles.css

h1 {
    text-align: center;
}

img {
  height: 300px;
  width: 300px;
  margin: 1px;
}

Images that we will be using. I took these images so you are free to use and distribute them. The link to download these images is provided at the bottom of the article.

Starter Code Output:
Screenshot-2024-07-03-223632

Centering Images Horizontally

Method 1: Using `text-align`

Add a div tag with a class selector called "main-container" to our index.html file.

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Centering Images Using CSS</title>
    <link rel="stylesheet" href="./styles.css" />
  </head>
  <body>
    <div class="main-container"> //---ADDED LINE ---
        <h1>Image Collection</h1>
        <img src="./colorado_1.jpg" />
        <img src="./colorado_2.jpg" />
        <img src="./london_1.jpg" />
        <img src="./london_2.jpg" />
    </div> //---ADDED LINE ---
  </body>
</html>

In our styles.css file, add the following code:

.main-container {
    text-align:center;
}

We can use text-align to center our images (the child element) because the div that they are now grouped within (the parent element) is a block level element and the text-align property only applies to block level elements.
You can think of this method as placing all the photos that we have on the top of our bookshelf side by side into a plastic container and then pushing the container to the middle of our bookshelf.

Output:
Screenshot-2024-07-03-223912

Method 2: Using Flexbox

Leaving the code in our index.html file unchanged, comment out the main-container selector that you just added in styles.css and add the following selector:

body {
  display: flex;
  justify-content: center;
}

We enable the flexbox layout mode by using display:flex(which arranges elements on our webpage side-by-side by default). Using justify-content moves all elements within the flex container (the body of our webpage in this case) to the center of the main-axis (which goes from left to right by default).

Output:
Screenshot-2024-07-03-224022

To make our webpage look more visually appealing, let's increase the space between our images and change the layout of our items using flex-direction. Using flex-direction changes the direction of our main axis so that it now runs from top to bottom instead of left to right. Therefore, we would use align-items (which controls the alignment of all items on the cross axis) instead of justify-content (which controls the alignment of all items on the main axis). If you are confused about the flexbox terminology here, refer to this article

Edit your styles.css file so that it contains the following code:

body {
  display: flex;
  flex-direction: column;
  align-items: center;
}

img {
  height: 300px;
  width: 300px;
  margin:10px;
}

h1 {
  text-align: center;
}

Output:
Screenshot-2024-07-03-224231

Questions:

Why does text-align: center only work when we group our images within the main-container div?
What happens to the main-axis and cross axis when we set flex-direction to column?

Answer to Questions

Question #1

The text-align property only applies to block level elements (such as div) and by default, images are inline elements.

Question #2

When we set flex-direction to column, our main-axis now runs from the top of the page to the bottom and our cross-axis now runs form the left of the page to the right. Therefore, our images are placed below the page title. You can think of the main-axis and cross-axis like the x and y axis on a grid; when we set flex-direction to column the x axis is switched with the y axis.

Center Images Vertically

Method 1: Using `display:block` and setting margins to `auto`

Comment out or remove all the code currently in styles.css except the starter code provided at the beginning of this article. Add the following code to the img selector:

display: block;
margin-left: auto;
margin-right: auto;

Since images are inline elements by default (meaning that they do not start on a new line), we force each image onto its own line by using display:block. Setting margin-left and margin-right to auto causes the browser to evenly distribute the remaining space on the left and right sides of the element, which centers the images vertically on the webpage.

Output:
Screenshot-2024-07-03-224345

Method 2: Using Flexbox

Edit your styles.css file so that it contains the following code:

body {
  display: flex;
  flex-direction: column;
  align-items: center;
}

h1 {
  text-align: center;
}

img {
  height: 300px;
  width: 300px;
  margin: 20px;
  display:block; //---ADDED LINE ---
}

Output:
Screenshot-2024-07-03-224345-1

Questions:

In our body selector, why do we use align-items:center instead of justify-content: center?
Why can we use display:block in our img selector in order for our images to center vertically?

Answer to Questions

Question #1

We use align-items:center instead of justify-content: center because we set flex-direction: to column. As explained in the answer to the previous question, our main-axis and cross-axis are now switched, so we use align-items to center our images vertically.

Question #2

Using display:blockforces each image onto its own line/stacks our images on top of each other. Similar to the previous analogy for centering images horizontally, you can think of both Methods #1 and #2 as placing all the photos that we have on the top of our bookshelf into a plastic container, one photo on top of each other, and then pushing the container to the middle of our bookshelf.

Center Images Both Horizontally and Vertically

Using Flexbox

Edit your styles.css file so that it contains the following code:

body{
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

h1 {
  text-align: center;
}

img {
  height: 300px;
  width: 300px;
  margin: 20px;
}

The reason that we need to include height:100vh along with align-items and justify-content is that justify-content only has an effect if there's free space left in our body flex container. By default the body container does not have any free space left over so we need to set height to 100vh, or 100% of the viewport height to center the images both horizontally and vertically on our webpage.

Output (with height:100vh removed and the border of the body container in red):
Screenshot-2024-07-03-224732

Output (with height:100vh added and the border of the body container in red):
Screenshot-2024-07-03-224809

Coding Challenge

Problem: On your personal website, you are creating an album of photos from your previous vacations to share with your family and friends. Using what you have learned in this article, and given the following starter code and images from the article (links to download can be found at bottom), fill in the code for themain-container and sub-container selectors so that your webpage match the output below:

Note: The photo sub-containers should be centered both horizontally and vertically within main-container (the body of the webpage).

Screenshot-2024-07-03-224928

index.html:

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Centering Images Using CSS</title>
    <link rel="stylesheet" href="./styles.css" />
  </head>
  <body>
    <nav>
      <ul>
        <li>Home</li>
        <li>About Me</li>
        <li>Photos</li>
        <li>Contact</li>
      </ul>
    </nav>
    <div class="main-container">
      <div class="sub-container">
        <h1>Colorado 2022</h1>
        <img src="./colorado_1.jpg" />
        <img src="./colorado_2.jpg" />
      </div>
      <div class="sub-container">
        <h1>London 2023</h1>
        <img src="./london_1.jpg" />
        <img src="./london_2.jpg" />
      </div>
    </div>
  </body>
</html>

styles.css

nav {
  background-color: antiquewhite;
}

nav ul{
  display: flex;
  font-size: 30px;
  list-style-type: none;
  font-weight: bold;
  justify-content: center;
}

nav ul li{
  margin-right: 25px;
  text-decoration: none;
  padding: 30px;
}

h1 {
  text-align: center;
}

img {
  height: 300px;
  width: 300px;
  margin: 20px;
}

.main-container {
  //ADD CODE HERE
  background-color: burlywood;
}

.sub-container{
  border: 3px solid black;
  //ADD CODE HERE
}

Answer to Coding Challenge

styles.css

nav {
background-color: antiquewhite;
}

nav ul{
display: flex;
font-size: 30px;
list-style-type: none;
font-weight: bold;
justify-content: center;
}

nav ul li{
margin-right: 25px;
text-decoration: none;
padding: 30px;
}

h1 {
text-align: center;
}

img {
height: 300px;
width: 300px;
margin: 20px;
}

.main-container {
display: flex;
justify-content: center;
align-items: center;
background-color: burlywood;
height: 100vh;
}

.sub-container{
border: 3px solid black;
display: flex;
flex-direction: column;
}

Key Takeaways

When centering images on a webpage, is it crucial to keep in mind the relationship between parent and child elements (such as main-container and the images nested inside it)
In CSS, you can center images both with and without Flexbox (CSS Flexible Box Layout)
However, using Flexbox will often be easier due to the control it gives you over responsive page layout and the fact that you will have to remember less CSS syntax/rules

Center Images using CSS

CSS Web Development

Introduction

Prerequisites

Starter Code and Images

Centering Images Horizontally

Method 1: Using `text-align`

Method 2: Using Flexbox

Questions:

Question #1

Question #2

Center Images Vertically

Method 1: Using `display:block` and setting margins to `auto`

Method 2: Using Flexbox

Questions:

Question #1

Question #2

Center Images Both Horizontally and Vertically

Using Flexbox

Coding Challenge

Key Takeaways

Dynamic and Static dispatch in C++

Guide through Serverless architecture

Introduction

Prerequisites

Starter Code and Images

Centering Images Horizontally

Method 1: Using text-align

Method 2: Using Flexbox

Questions:

Question #1

Question #2

Center Images Vertically

Method 1: Using display:block and setting margins to auto

Method 2: Using Flexbox

Questions:

Question #1

Question #2

Center Images Both Horizontally and Vertically

Using Flexbox

Coding Challenge

Key Takeaways

Method 1: Using `text-align`

Method 1: Using `display:block` and setting margins to `auto`