A plain English explanation of why the same website can look and behave differently depending on what you use to view it.
If you have ever looked at your website on your phone and noticed it looks slightly different to how it appears on your laptop, or asked a friend to check it and they describe something slightly different to what you see — you are not imagining things. The same website genuinely can look different depending on the device, screen, browser, and settings used to view it. This is normal, it is expected, and understanding why it happens is useful for anyone who owns a website.
The most obvious reason a website looks different on different devices is simply that the screens are different sizes. A desktop monitor might be 27 inches wide. A phone screen might be 6 inches. A tablet sits somewhere in between. A website has to work across all of them.
Well-built websites use responsive design — code that detects the screen width and adjusts the layout accordingly. On a wide desktop screen, content might sit in three columns side by side. On a phone, those same three columns stack vertically so they are readable without zooming. The content is identical — the layout adapts.
This is why a website on your phone looks different to the same site on your desktop. It is supposed to. The alternative — a fixed-width site that looks identical on every screen — works well on desktop and is unreadable on mobile without pinching and zooming. Responsive design is the solution, and the layout difference between devices is the result.
Two screens can be physically the same size but display images and text very differently because of resolution — the number of pixels packed into the screen. Modern smartphones have extremely high pixel density, which is why photos and text look sharp and crisp on them. Older monitors may have lower resolution, making the same content look slightly softer.
High-resolution screens — often called Retina displays on Apple devices — display images at double the pixel density. An image that looks perfectly sharp on a standard screen may look slightly blurry on a high-resolution screen if it was not prepared at sufficient size. A well-built website accounts for this by serving appropriately sized images to different screen types.
Colour reproduction also varies between screens. A monitor calibrated for photo editing will display colours more accurately than a budget laptop screen. Two people looking at the same website can see noticeably different colours simply because their screens are different. This is a hardware limitation — no amount of code can make every screen display colours identically.
Chrome, Firefox, Safari, Edge, and Opera are all browsers — but they are not identical. Each one has its own rendering engine, which is the software that reads the website's code and turns it into what you see on screen. Different rendering engines interpret the same code in slightly different ways.
Most of the time these differences are minor — a slightly different default font size, a marginally different treatment of spacing, a subtle variation in how a shadow or border radius appears. Occasionally the differences are more significant, particularly with newer CSS features that some browsers support and others do not yet, or with older browsers that handle modern code less gracefully.
A thorough developer tests their work across multiple browsers and addresses the differences. But achieving pixel-perfect identical appearance across every browser is not realistic — and not necessary. What matters is that the site looks professional, functions correctly, and provides a good experience in all the major browsers.
Safari on iOS deserves a specific mention because it behaves differently to Chrome and Firefox in several notable ways. Apple controls how web content is rendered on iPhones and iPads, and Safari has its own quirks — particularly around how it handles fonts, form elements, video playback, and certain CSS features. A site that looks and behaves perfectly in Chrome may need specific adjustments to work equally well in Safari on an iPhone. Good developers test on real iOS devices, not just desktop browsers.
Windows, macOS, iOS, and Android all handle fonts, colours, and interface elements differently. The default fonts available on a Windows machine are not the same as those on a Mac. A website that specifies a font not available on the visitor's device will fall back to a substitute — which may be similar but not identical. Text rendering — the way letterforms are drawn on screen — also differs between operating systems, meaning the same font can look subtly different on Windows compared to a Mac.
Form elements — dropdown menus, checkboxes, date pickers — are often styled by the operating system rather than the website, which is why the same contact form can look noticeably different on an iPhone compared to an Android device. Overriding these with custom styling is possible but adds complexity and must be done carefully.
Many people — particularly those with visual impairments — browse with their browser zoom set above the default 100%, or with a larger default text size configured in their browser or operating system settings. A well-built website handles this gracefully, reflowing content sensibly at larger text sizes. A poorly built one breaks — text overlaps, buttons become inaccessible, layouts fall apart.
This is another reason why testing a website at different zoom levels is part of thorough development. The experience of a visitor who browses at 125% or 150% zoom should be good, even if it looks different to the 100% view the developer saw during testing.
Most modern operating systems and browsers offer a dark mode option that inverts or adjusts colour schemes across the interface. Some websites are built to detect dark mode and adjust their appearance accordingly — swapping white backgrounds for dark ones, adjusting text colours, modifying images. Others are not, and dark mode browsers may apply their own transformations to the page, sometimes with unpredictable results.
A visitor using dark mode may see your website looking noticeably different — sometimes better, occasionally worse — than you intended. Whether to build dark mode support into a website is a design decision, but being aware that some visitors will see a different colour scheme is useful context.
A good developer cannot make a website look absolutely identical on every device, screen, browser, and setting combination — nobody can. What they can do is ensure the site looks professional, functions correctly, and provides a genuinely good experience across the widest possible range of conditions. That means:
The goal is not uniformity — it is a consistently good experience. A visitor on an old Android phone and a visitor on a new MacBook Pro will see your website differently. Both should come away with a professional impression of your business.
