How do you develop a responsive website?

With an internet increasingly accessed from mobile devices, it’s no longer enough to have a static website design that only looks good on a computer screen.

Not to mention, you also have to consider tablets, 2-in-1 laptops, and different smartphone models with different screen dimensions when coming up with a design.

So slapping your content into a single column and calling it quits isn’t going to cut it.

With responsive web design, you can make sure your website looks its best on cell phones, tablets, laptops, and desktop screens.

And that improvement in user experience means higher conversions and business growth.

This guide will give you everything you need to know about responsive website design, including definitions, a step-by-step walkthrough, examples, and more.

What Is Responsive Web Design?

Responsive design is an approach to web design that makes your web content adapt to the different screen and window sizes of a variety of devices.

For example, your content might be separated into different columns on desktop screens, because they are wide enough to accommodate that design.

If you separate your content into multiple columns on a mobile device, it will be hard for users to read and interact with.

Responsive design makes it possible to deliver multiple, separate layouts of your content and design to different devices depending on screen size.

It’s not enough for your website to look good on a computer screen. Tablets, 2-in-1 laptops, and smartphones are all part of the equation... and this guide covers everything you need to know about responsive design 🤳

Responsive Web Design vs Adaptive Design

The difference between responsive design and adaptive design is that responsive design adapts the rendering of a single page version. In contrast, adaptive design delivers multiple completely different versions of the same page.

They are both crucial web design trends that help webmasters control how their site looks on different screens, but the approach is different.

With responsive design, users will access the same basic file through their browser, regardless of device, but CSS code will control the layout and render it differently based on screen size. With adaptive design, there is a script that checks for the screen size, and then accesses the template designed for that device.

Why Responsive Design Matters

If you’re new to web design, development, or blogging, you might wonder why responsive design matters in the first place.

The answer is simple. It’s no longer enough to design for a single device. Mobile web traffic has overtaken desktop and now makes up the majority of website traffic, accounting for more than 51%.

Mobile, tablet, desktop market share

When over half of your potential visitors are using a mobile device to browse the internet, you can’t just serve them a page designed for desktop. It would be hard to read and use, and lead to bad user experience.

But that’s not all. Users on mobile devices also make up the majority of search engine visits.

Mobile search traffic

Finally, over the last few years, mobile has become one of the most important advertising channels. Even in a post-pandemic market, mobile ad spending is growing 4.8% to $91.52 billion.

Whether you choose to advertise on social media or use an organic approach like YouTube SEO, the vast majority of your traffic will come from mobile users.

If your landing pages aren’t optimized for mobile and easy to use, you won’t be able to maximize the ROI of your marketing efforts. Bad conversion rates will lead to fewer leads and wasted ad spend.

Are WordPress Sites Responsive?

Whether or not WordPress sites are responsive depends on the theme of your WP site. A WordPress theme is the equivalent of a template for a static website and controls the design and layout of your content.

If you use a default WordPress theme, like Twenty Twenty, the design is responsive, but since it’s a single-column design, you might not realize it when looking at it on different screens.

If you use another WordPress theme, you can test if it’s responsive or not by comparing how it looks on different devices or using Chrome Developer Tools.

The Building Blocks of Responsive Web Design

In this section, we’ll cover the underlying foundation for responsive website design and its different building blocks.

  1. CSS and HTML

  2. Media Queries

  3. Fluid Layouts

  4. Flexbox Layout

  5. Responsive Images

  6. Speed


The foundation of responsive design is the combination of HTML and CSS, two languages that control the content and layout of a page in any given web browser.

HTML mainly controls the structure, elements, and content of a webpage. For example, to add an image to a website, you have to use HTML code like this:

<img src="image.gif" alt="image" class=”full-width-img”>

You can set a “class” or “id” that you can later target with CSS code.

You could also control primary attributes such as height and width within your HTML, but this is no longer considered best practice.

Instead, CSS is used to edit the design and layout of the elements you include on a page with HTML. CSS code can be included in a <style> section of a HTML document, or as a separate stylesheet file.

For example, we could edit the width of all HTML images at the element level like this:

img {width: 100%;}

Or we could target the specific class “full-width-img” by adding a period in front.

.full-width-img {width: 100%;}

You can also control the design beyond just height, width, and color. Using CSS like this is how you make a design responsive when you combine it with a technique called media query.

Media Queries

A media query is a fundamental part of CSS3 that lets you render content to adapt to different factors like screen size or resolution.

It works in a similar way to an “if clause” in some programming languages, basically checking if a screen’s viewport is wide enough or too wide before executing the appropriate code.

@media screen and (min-width: 780px) {.full-width-img {margin: auto;width: 90%;}

If the screen is at least 780 pixels wide, “full-width-img” class images will take up 90% of the screen and be automatically centered by equally wide margins.

Fluid Layouts

A fluid layout is an essential part of modern responsive design. In the good old days, you would set a static value for every HTML element, like 600 pixels.

A fluid layout relies instead on dynamic values like a percentage of the viewport width.

This approach will dynamically increase or decrease the different container element sizes based on the size of the screen.

Flexbox Layout

While a percentage-based layout is fluid, many designers and web developers felt it was not dynamic or flexible enough. Flexbox is a CSS module designed as a more efficient way to lay out multiple elements, even when the size of the contents inside the container is unknown.

A flex container expands items to fill available free space or shrinks them to prevent overflow. These flex containers have a number of unique properties, like justify-content, that you can’t edit with a regular HTML element.

It’s a complicated topic, so if you want to use it in your design, you should read CSS Tricks’ flexbox guide.

Responsive Images

The most basic iteration of responsive images follows the same concept as a fluid layout, using a dynamic unit to control the width or height. The sample CSS code we covered earlier already accomplishes this:

img {width: 100%;}

The % unit approximates to a single percentage of the width or height of the viewport and makes sure the image remains in proportion to the screen.

The problem with this approach is that every user has to download the full-sized image, even on mobile.

To serve different versions scaled for different devices, you need to use the HTML srcset attribute in your img tags, to specify more than one image size to choose from.

<img srcset="large-img.jpg 1024w,
middle-img.jpg 640w,
small-img.jpg  320w"

WordPress automatically uses this functionality for images included in posts or pages.


When you’re attempting to create a responsive design for your website, the loading speed should be a top priority.

Pages that load in 2 seconds have an average 9% bounce rate, while pages that take 5 seconds lead to a 38% bounce rate.

Your approach to responsiveness must not block or delay your page’s first render any more than it needs to.

There are several way you could make your pages faster. Optimizing your images, implementing caching, minification, using a more efficient CSS layout, avoiding render-blocking JS, and improving your critical rendering path are all great ideas you should consider.

You could also try to implement Google AMP for your mobile pages, but in our Google AMP case study, our mobile leads dropped by a whopping 59%.

Common Responsive Breakpoints

To work with media queries, you need to decide on the “responsive breakpoints” or screen size breakpoints. A breakpoint is the width of the screen where you use a media query to implement new CSS styles.

Common screen sizes

  • Mobile: 360 x 640

  • Mobile: 375 x 667

  • Mobile: 360 x 720

  • iPhone X: 375 x 812

  • Pixel 2: 411 x 731

  • Tablet: 768 x 1024

  • Laptop: 1366 x 768

  • High-res laptop or desktop: 1920 x 1080

If you choose a mobile-first approach to design, with a single column and smaller font sizes as the basis, you don’t need to include mobile breakpoints — unless you want to optimize the design for specific models.

So you can create a basic responsive design with just two breakpoints, one for tablets and one for laptops and desktop computers.

Bootstrap’s Responsive Breakpoints

As one of the first, and most popular, responsive frameworks, Bootstrap led the assault on static web design and helped establish mobile-first design as an industry standard.

As a result, many designers to this day still follow Bootstrap’s screen-width breakpoints.

They use media queries to target landscape phones (576px), tablets (768px), laptops (992px) and extra large desktop screens (1200px).

How to Make Your Website Responsive

Now that you’re familiar with the building blocks, it’s time to make your website responsive.

  1. Set Your Media Query Ranges (Responsive Breakpoints)

  2. Size Layout Elements with Percentages or Create a CSS Grid Layout

  3. Implement Responsive Images

  4. Responsive Typography For Your Website Text

  5. Test Responsiveness

Set Your Media Query Ranges (Responsive Breakpoints)

Set your media query ranges based on the unique needs of your design. For example, if we wanted to follow the Bootstrap standards for our design, we would use the following media queries:

  • 576px for portrait phones

  • 768px for tablets

  • 992px for laptops

  • 1200px for large devices

Size Layout Elements with Percentages or Create a CSS Grid Layout

The first and most important step is to set up different sizes for different layout elements depending on the media query or screen breakpoint.

The number of layout containers you have will depend on the design, but most websites focus on the elements listed below:

  • Wrapper or Container

  • Header

  • Content

  • Sidebar

  • Footer

Using a mobile-first approach, you can style the main layout elements like this (with no media query for the basic styles for mobile phones):

#wrapper {width:95%;  margin: 0 auto; }#header {width:100%; }#content {width:100%; }#sidebar {width:100%; }#footer {width:100%; }

// Small devices (landscape phones, 576px and up)@media (min-width: 576px) {

// Medium devices (tablets, 768px and up)@media (min-width: 768px) {#wrapper {width:90%;  margin: 0 auto; }#content {width:70%; float:left; }#sidebar {width:30%; float:right; }

// Large devices (desktops, 992px and up)@media (min-width: 992px) { ... }}

// Extra large devices (large desktops, 1200px and up)@media (min-width: 1200px) {#wrapper {width:90%;  margin: 0 auto; }}

In a percentage-based approach, the “float” attribute controls which side of the screen an element will appear on, left, or right.

If you want to go beyond the basics and create a cutting-edge responsive design, you need to familiarize yourself with the CSS flexbox layout and its attributes like box-sizing and flex.

Implement Responsive Images

One way to make sure that your images don’t break is merely using a dynamic value for all pictures, as we covered earlier.

img {width: 100%;}

But that won’t reduce the load placed on your mobile visitors when they access your website.

Make sure you always include a srcset that with different sizes of your photo when you add images to your pages.

Doing this manually can be quite time-consuming, but with a CMS like WordPress, it automatically happens when you upload media files.

Responsive Typography For Your Website Text

The main focus of responsive web design is on the responsiveness of the layout blocks, elements, and media. Text is often treated as an afterthought.

But for a truly responsive design, you should also adjust your font-sizes appropriately to match screen size.

The easiest way to do so is to set a static value for font-size, like 22 px, and adapt it in each media query.

You can target multiple text elements at the same time by using a comma to separate each one.

@media (min-width: 992px) {body, p, a, h4 {font-size: 14px;}}

Test Responsiveness

First, you want to test whether your site is mobile-friendly with Google’s mobile-friendly test. Simply enter the URL of your website and click the “test URL” button to get the results.

Google’s Mobile-Friendly Test

Don’t worry if it takes a while to fetch your site. That doesn’t reflect your page loading speed.

If you followed the steps outlined in this article, it should say that you have a mobile-friendly website.

Then you want to test your site on multiple screen sizes with a tool like Chrome developer tools.

Press CTRL + Shift + I on Windows computers, or Command + Option + I on Macs to open the relevant device view. From here, you can select the mobile device or tablet of your choice to test the responsiveness of your design.

Testing responsive & mobile layouts in Chrome

There are a couple of questions you want to answer when going through this process.

  • Does the layout adjust to the correct amount of columns?

  • Does the content fit well inside the layout elements and containers on different screens?

  • Do the font sizes fit each screen?

CSS Units and Values for Responsive Design

CSS has both absolute and relative units of measurement. An example of an absolute unit of length is a cm or a px. Relative units or dynamic values depend on the size and resolution of the screen or the font sizes of the root element.

PX vs EM vs REM vs Viewport Units for responsive design

  • PX – a single pixel

  • EM – relative unit based on the font-size of the element.

  • REM – relative unit based on the font-size of the element.

  • VH, VW – % of the viewport’s height or width.

  • % – the percentage of the parent element.

A new web designer or developer should probably stick with pixels for text because they are the most straight-forward unit of length in CSS.

But when setting the width and max-width of images and other elements, using % is the best solution. This approach will make sure the components adjust to the screen size of every device.


There are a lot of different elements that go into responsive web design. Without a basic understanding of HTML and CSS, it can be easy to make mistakes.

But through familiarizing yourself with the different building blocks, analyzing the examples with web dev tools, and testing as you go using the sample code, you should be able to make your website responsive without any major issue.

If that sounds too much to achieve, you can always get in touch with one of Webalytics specialists to assist you with any of the above.

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