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Lead Designer

Sam Leonard-Rendell

Back in 2019, we created something that resonated with designers everywhere: a series of posters bringing Jakob Nielsen's usability heuristics to life. These principles, <a href="https://www.nngroup.com/articles/ten-usability-heuristics/">originally outlined in his 1994 article for The Nielsen Norman Group</a>, struck a chord with so many people that we've given them a fresh look and a new lease of life.Here's the thing about usability heuristics, they're not rigid rules you have to follow to the letter. Think of them more as guiding principles that form the bedrock of solid usability practices. We've leaned on these time and again <a href="https://sidigital.co/services/design/digital-design">when designing interfaces</a> or digging into usability test results. They give us a clear framework to work within and align our thinking.

Totally free, no strings attached, we promise.

Download our 10 Usability Heuristics Posters

Here at the Si digital studio, we wanted our walls to reflect the work we do, so Jakob Nielsen's original article got us thinking, why not turn these "10 Usability Heuristics" into something visual and inspiring?Fast forward to today, and these posters are printed, framed, and hanging in our studio. They've become such a <a href="https://sidigital.co/services/design/digital-design">valuable part of our daily work</a> that we wanted to share them in their new form with the wider design community.This Lab Note showcases a couple of our 10 posters, and we're making them available as free downloads in PDF, PNG, and JPG formats. We hope they inspire your work as much as they've inspired ours. Feel free to share them with your team.

Bringing heuristics to life in our studio

It’s estimated that around 1 in 12 men (8%) and 1 in 200 women have some form of colour blindness. In the UK, this means that there are approximately 2.7 million people affected, a considerable amount of the population, but they are often forgotten when it comes to designing websites and user interfaces.Here at Si digital we consider user experience and accessibility throughout every project. We use a variety of tools and techniques to help us understand visual impairments and use this knowledge to make our websites more usable and less frustrating for people who are colour blind.

Who is affected?

There are many types of colour blindness with different degrees of severity. It’s a common myth that people with colour blindness only see in black and white. Although this can be true, monochromacy – also known as total colour blindness – is extremely rare, with an estimated 1 in 33,000 people affected. This severe visual impairment only allows an individual to see in greyscale.An important factor to remember is that for most people with colour blindness, distinguishing between different colours is not too difficult; it’s telling the difference between shades and brightness levels of similar colours which causes issues.The more common condition is red-green colour blindness, which is split into two groups. A person with protanomaly has reduced sensitivity to red light. Red, orange, and yellow hues tend to shift towards green and appear less saturated. A person with deuteranomaly has reduced sensitivity to green light and will have difficulty distinguishing between blue, yellow, violet, reds, blues, and greens.

What is colour blindness?

For a long time, the difficulties that arise from colour blindness have been ignored, not only in website design, but also television, movies, and especially video games. There are many cases of users not being able to play a game or being unable to progress because of essential UI elements being indistinguishable to somebody who suffers from colour blindness.Take this example from The Witcher 3...

Colour in the wild

See how the red markers on the floor become near invisible when switching to red-green colour blindness.The game features an ability to use heightened senses to follow scents, track footprints, and find clues. However, the game developers chose a deep red colour as a marker, so there have been many users complaining that they couldn’t see these markers very well (or at all). A simple colour change or the option to change colours would have made this game more accessible.Colour blindness is a matter which needs to be taken seriously due to the high percentage of the population with vision impairments. If your website or application is particularly unoptimised, you could be losing a large amount of customers. For example, if a user can’t differentiate between a series of icons because of clashing colours and lack of contrast, that user could get frustrated and find an alternate service. If that is the experience of every potential customer who suffered from colour blindness, you’re losing over 8% of potential sales – for a business with £10,000,000 in revenue, that company could potentially lose a huge £800,000 in sales.

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Although colour blindness can cause huge problems for users, it’s actually quite simple to combat. If you’re aware of the issues, then you’re already halfway there.<h3>1. Use contrasting colours</h3>Even people who have monochromacy still have a sense of contrast – the scaled difference between light and dark. To ensure your website is readable for people with visual impairments, you must make sure your content contrasts well with your background. For example, black text on a white background will have a high level of contrast and readability. Whereas yellow text on a white background has a low level of contrast and will be barely readable, even for people with full vision!

Designing with colour blindness in mind

<h3>2. Use different shades rather than multiple colours</h3>A monochromatic colour scheme — not to be confused with full colour blindness, monochromacy – makes use of multiple shades of one colour, rather than using various different colours. This will effectively minimise colour-related frustration, and is a great way to include contrast in your designs. A monochromatic colour scheme doesn’t have to be black and white; using multiple shades of blue, we can create a visually pleasing design with complete readability.

<h3>3. Experience colour blindness yourself while designing</h3><h4>Colour blindness simulation in Adobe Photoshop</h4>There are many free tools available that can mimic the effects of colour blindness, allowing you to understand how a colour blind person would see to ensure that your user interfaces work just as you intended them to. Photoshop has its own — slightly hidden away — proof setup feature; simply go to View > Proof Setup, and then you can choose between protanopia and deuteranopia. When you’re done testing, simply switch back to monitor RGB.<h4>Colour blindness simulation in Figma</h4>Unfortunately, there is no native support for Figma colour testing; however, there are various plugins that allow you to do the exact same thing. We recommend <a href="https://www.figma.com/community/plugin/1115550442410459794/color-blind" target="_blank" rel="noopener noreferrer">Color Blind</a>, a free plugin that shows you in real time what people with common colour vision impairments will see.<h4>Colour blindness simulation in Browser</h4>We use a Google Chrome add-on called <a href="https://chromewebstore.google.com/detail/colorblindly/floniaahmccleoclneebhhmnjgdfijgg?pli=1" target="_blank" rel="noopener noreferrer">Colorblindly</a> that lets you simulate colour blindness on live websites or in a testing environment. This is a handy tool for colour and contrast testing as it offers multiple viewing modes, including full monochromacy.

<h3>4. Choose colour combinations carefully</h3>Unfortunately, as designers, we don’t always get to choose the colours that we use in our designs; sometimes, we’re limited by brand guidelines. But where possible, it’s wise to choose and test your primary and secondary colours before you establish a brand. Below is a chart of colour combinations that you should avoid using.If in doubt, avoid colour altogether and go for a simple black/white, high-contrast colour scheme!

<h3>5. Use texture in place of colour</h3>When designing things like graphs and infographics, consider making use of texture or visual patterns to help differentiate between two colours. For example, take the pie chart below. A user with protanopia would find it hard to differentiate between the different slices due to the colours being too similar. However, if we simply add some texture or patterns, the graph is 100% more readable.

<h3>6. Avoid using colour alone as an indicator</h3>When designing elements like forms and complicated interfaces, you shouldn’t use colour alone as an indicator. Take the forms below as an example. The one on the left only uses colour as an indicator that something went wrong. A person with normal vision will be able to see that the email field has turned red, indicating there has been some kind of error. However, to a person with deuteranomaly, the green of the success field is indistinguishable from the red of the error field. The best way to combat this issue is to use some kind of icon, symbol, or label to indicate that an error has occurred, as seen on the right.

The most important lesson to learn here is that unless you’re absolutely certain that somebody with colour blindness can differentiate between the colours you have chosen, then you should never use colour alone to indicate something important. Where possible, use icons, text, shapes, textures, or other visual cues as well as colour when communicating information to users.There are many ways to test for accessibility; however, these tools aren’t always fully accurate – ultimately, the best way to see if your design is suitable is to perform real UX audits. It’s likely that you know somebody who is colour blind; why not get them to review your design?What we see as designers and developers isn’t always what your users see; they could be colour blind, using a screen reader, or looking at your website on a 3″ smartphone from 2007. Creating websites that are accessible to everyone is essential and should be part of any good design process.If you would like to speak to us about your new project and how we ensure we always deliver the ultimate, accessible user experience, please <a href="https://sidigital.co/contact">get in touch</a>.

Conclusion

Have a read of some of our other articles

How to design for colour blindness: best practices for accessibility

There’s a lot to organise and the pressure’s on to get things right. With all this to contend with, it’s important to accurately identify the key insights. This improves efficiency and provides value to your clients with clear feedback.We have tried many different ways of recording feedback with participants. Each method became convoluted, making it harder to analyse data at the end of a test. So, we began looking for ways to improve our process.

User tests can be full-on

We have recently been looking at <a href="https://www.youtube.com/watch?v=8AKWYH1EzJI" target="_blank" rel="noopener noreferrer">Design Sprints and how user testing is compressed into one day</a>. This technique is simple in its approach and has been successful for us. It removes the bloat and keeps the work focussed. Today, we want to share and break down this way of working.

Stay simple and don’t over complicate

Before starting a user test, you will need:<ul class="list-bullet"><li value=1>Whiteboard / whiteboard wall</li><li value=2>Whiteboard markers</li><li value=3>Sharpies</li><li value=4>A pad of blue Post-its</li><li value=5>A pad of pink Post-its</li></ul>Now that you have your equipment, you can begin to record your user feedback. We usually test with 5 participants as this tends to be the sweet spot of not too many or too few. <a href="https://www.nngroup.com/articles/why-you-only-need-to-test-with-5-users/" target="_blank" rel="noopener noreferrer">What Nielsen Norman Group wrote about testing with 5 users still holds true</a>. You can find up to 85% of usability issues with 5 participants. ‘Add more and more users, you learn less and less’.Before the first person arrives, you will need to divide up your whiteboard. Using a whiteboard marker, split the board into 5 columns. Add the names of your participants across the top. Down the left-hand side, add rows and label each according to the task or page you are looking to test.

Preparing for user testing feedback

As you do your user tests, it is important to make quick notes as you go. We tend to analyse our user tests in pairs to prevent any misinterpretation of comments. This is where we use our post-its to record different types of feedback. However, make quick, rough notes before transferring them to post-its at the end. We use blue post-its for positive comments and pink post-its for negative. A negative comment could mean a participant struggles or has to think about what to do next. Or they might communicate their problem out loud. Write these down as they are super important.Once you have your feedback, stick the post-its into the relevant row for that participant. As you do this, discuss and compare the feedback received and see where there is overlap.

Recording user testing feedback

Repeat this process for each of your user testing participants. Making notes as you go, then writing down the feedback on the relevant post-its at the end of each test. Once you have all five up on the board, you’re ready to begin looking for patterns. They should really jump out at you!If you take a step back from the board, it should become quite clear where the problem areas are. Look closer and you should be able to group specific insights. This will help you to build a picture of where the most common issues are.

Repeat for each user test

This is a simple and quick technique to record user testing feedback that a group of you can do together. It helps improve collaboration and the process of gathering insights.

That’s it

A simple way to record your user testing feedback

The 10 Usability Heuristics – updated for 2026

When it comes to branding, colour accuracy matters. When we’re <a href="https://sidigital.co/services/design/branding">building brands</a> for our clients, we can’t afford to rely on guesswork and varying colour profiles on different displays. Pantone guides give us a definitive, real-world reference point that ensures our colours are consistent across the board.It’s the kind of investment that reflects our focus on quality. We’ve been doing this for over two decades, and we know that the detail makes a difference. When a client’s brand guidelines specify Pantone 185 C, we want to show them exactly how that looks across print, not as an approximation on screen.

Why we made the investment

Pantone actually covers everything from print through to textiles, so it can be tricky knowing which guides to buy. <a href="https://sidigital.co/services/design/graphic-design">For graphic design</a>, there are Formula guides, Colour Bridge guides, Pastels & Neons, Metallics, and CMYK guides.We were torn between Formula Guides and Colour Bridge guides. Formula Guides simply show the Pantone colour in its pure form, printed on coated or uncoated paper. Colour Bridge guides show the Pantone colour, as well as its process CMYK match. It also gives us breakdowns of the Pantone colour in RGB and as a HEX code <a href="https://sidigital.co/services/design/digital-design">for digital, too</a>.We went with Colour Bridge guides rather than Formula guides as we can see the Pantone colour directly next to its process equivalent. This is really useful when we’re working on projects that cover both print and digital, or when a client’s budget means digital printing rather than spot colour.The majority of our print work ends up being produced using CMYK, so having that direct comparison helps us manage expectations and make informed decisions about colour reproduction. We can have honest conversations with clients about how their brand colours translate across different printing methods.

The guide dilemma

Here's something many people don't realise: Pantone guides have a shelf life. The colours fade and shift over time, especially when exposed to light. Here’s how you can help keep your Pantone guides in peak condition:<ul class="list-bullet"><li value=1>Replace them every 12 to 18 months to ensure colour accuracy.</li><li value=2>Keep them in their original sleeves when you’re not using them.</li><li value=3>Avoid leaving them in direct sunlight.</li></ul>It might seem over the top, but if we’re going to rely on these guides for accurate colour matching, they need to stay accurate.

Keeping them fresh

Given the investment (and yes, Pantone guides aren’t cheap), we’ve designated a specific home for our new guides in the studio. They live in a drawer, in their protective sleeve, away from coffee cups, curious hands, and the general chaos of a busy creative studio.We’ve also made sure the whole team knows they’re there, and how to use them properly. No bending pages, no leaving them open on desks, and definitely not lending them out. These are tools, not coffee table books.

Safe & secure 

It’s a pretty small purchase in the grand scheme of things, but it’s one of those investments that quietly improves the quality and accuracy of our work. Better colour accuracy means fewer surprises during print, happier clients, and a happy design team.If you’re curious about how we approach colour in your project, or you’d like to see your brand colours in the Pantone flesh, just ask. We’re always happy to geek out about this stuff.

The bottom line

Since its announcement at WWDC in June, Apple’s new Liquid Glass UI design for its 2026 (and beyond) operating systems has proved polarising. With its transparent, content-manipulating effects and reactive components, it’s a bold step away from the flat, static look we’ve grown accustomed to since Apple launched iOS 7 back in 2013, and an even bolder progression from the skeuomorphic designs we were used to before that.But what if we’ve been looking at Apple’s Liquid Glass in the wrong way? This isn’t about surface-level design trends or flashy animations. It’s about the future of technology and how we interact with it.

Apple’s Liquid Glass design language was launched yesterday with iOS 26, and as the world installs this new design system onto their phones, watches, headsets, tablets, laptops, and TVs, it’ll take time for users to adjust to this new look and way of interacting with their devices.What many people haven’t yet realised is that the way we interact with our devices is changing. With virtual reality (VR) and augmented reality (AR) becoming more prevalent, the line between the real world and the digital world is beginning to blur more and more. The <a href="https://www.fortunebusinessinsights.com/industry-reports/infographics/virtual-reality-market-101378" target="_blank" rel="noopener noreferrer">VR industry is expected to be worth $123bn</a> by 2032. To put that into context, it was only worth $16.32bn in 2024. So, the transition in UI design as we focus more on VR & AR is inevitable, and likely for the good of the usability of those devices in the future.When Apple launched the iPhone in 2007, we were at a similar juncture for UI and UX, but we didn't realise it at the time. We’d been using clunky phones with physical keyboards and untouchable content for decades, and suddenly we had a device where we could touch the content we were interacting with. Note-taking, calendars, compasses, and more. Getting users to understand this resulted in skeuomorphic design – a style that brought relatable, understandable, real-world context to digital applications and interactions. It was about educating users in a manageable way that didn’t feel a million miles away from using a real notepad or a real calendar.

A new era for UI design begins today

After six years of training us, Apple made the move away from skeuomorphic design across to flat design with iOS 7. That style has developed, changed, and grown into what we’ve now become familiar with in iOS 18, macOS Sequoia, and visionOS 2. Liquid Glass might look like pure visual polish, but it’s doing something much more important: teaching us a new way to interact. Just as skeuomorphism helped us move away from physical buttons to touchscreens, Liquid Glass is quietly preparing us for a future that isn’t restricted to screens at all. We’re moving into a new era where digital worlds are layered over the real world, and how we interact with it depends on more than just our fingertips. This shift needs a different kind of interface. One that listens, watches, and responds. It feels alive. This is where multimodal UI design comes in.

Multimodal UI design language relies on more than just a single input, like touch. It’s built around voice, gaze, movement, and touch. It’s this that bridges the gap between what we know as an OS, and what an OS will become. Take visionOS, or Meta Horizon OS. Both are examples of multimodal interfaces. Not only is the content overlaid onto the real world, it’s controlled by the direction you’re looking, or by your voice as you ask it to perform an action or task. And, especially in vision OS, these overlaid interface elements are designed to interact and work with the world around them, rather than just sitting on top.

Liquid Glass isn’t just multimodal, it’s reactive. Built around a system of free-floating elements and components, the interface dynamically adjusts to how you use it. These elements aren’t locked to a fixed screen either; they appear when you need them and fade away when you don’t.It’s this fluidity that makes Liquid Glass the ideal UI for overlaying on the real world. Elements can subtly sink into the surroundings when idle and reappear when they’re relevant. If your environment changes, the UI responds and reveals what’s behind it by taking a step back. It’s a design system that’s as understanding and perceptive as you are.Apple’s approach is also about unifying an experience across their device ecosystem. As all these devices begin to merge into a spatial realm, consistency will be key. Liquid Glass isn’t limited to iPhones; it’s become the universal design language used across all of Apple’s devices. This is an important shift. Historically, Apple has tended to update the iPhone and iPad visual designs ahead of the Mac. For example, when Apple launched its flat design system with iOS 7, macOS Mavericks still maintained its skeuomorphic design. The fact Apple is rolling Liquid Glass out across its entire suite of operating systems sends a clear message: this is the future, and it’s starting now.

In contrast, Google has taken a <a href="https://blog.google/products/android/material-3-expressive-android-wearos-launch/" target="_blank" rel="noopener noreferrer">very different approach</a> with its latest design system, Material 3. Its punchy colours, expressive typographic treatments, and bold graphic devices feel optimised for rectangular screens. Perfect for phones and tablets. But as we move into a world where interfaces begin to extend beyond the screen, this look and feel will quickly fall behind and become limiting.Material 3 is firmly rooted as a visual language for traditional devices. It’s difficult to imagine these vibrant, highly-saturated colours and decorative sticker-like layers translating to spatial environments or multimodal interfaces where the UI has to adapt to different lighting, varying depths, and real-world context.Compared to Apple’s Liquid Glass design system, Material 3 feels like it was designed solely for mobile-era aesthetics. We imagine it’ll only be a matter of time before Android follows suit.

Material 3: Beautifully screen-bound

Despite its future-focussed foundations, Liquid Glass is a polarising design language, and this is primarily for two reasons: accessibility and its association with past design trends. Stylistically, it’s been compared to Windows Vista, which launched in 2007 with a <a href="https://en.wikipedia.org/wiki/Windows_Aero" target="_blank" rel="noopener noreferrer">new design style called Aero</a>. Aero marked a dramatic move away from the blocky era of Windows XP, and just like Liquid Glass today, it divided opinion. But the intent behind Liquid Glass is very different to Windows Vista. Windows Vista was about reskinning a system users were already very familiar with to make it feel more modern. Liquid Glass is about the shift from screens to spatial, immersive experiences.Accessibility is a much bigger concern. With its glassy, translucent design, Liquid Glass definitely poses some issues with legibility and contrast, especially against high-contrast backgrounds. This is surprising coming from Apple. They’ve long been seen as leaders when it comes to inclusive design; <a href="https://www.apple.com/uk/accessibility/" target="_blank" rel="noopener noreferrer">it’s one of their core values</a>.However, it’s important to remember that Apple gives users a deep level of accessibility customisation so they can hone their devices to work for them. And Apple has always made iterative improvements as time goes on. Remember when iOS 7’s animations were <a href="https://abcnews.go.com/Technology/apple-ios-literally-making-users-sick/story?id=20385379" target="_blank" rel="noopener noreferrer">making users motion sick</a>? Or when users said the <a href="https://www.nbcnews.com/tech/tech-news/fonts-dont-lie-thin-ios-7-os-x-flna6c10245346" target="_blank" rel="noopener noreferrer">system typefaces were too thin</a>? Apple responded by adjusting the design language.Liquid Glass is following a similar path. We’re entering uncharted territory with spatial, multimodal user interfaces. There will be missteps. But just as with past transitions, refinement will come with time, and with real-world feedback from users pushing the boundaries of how we interact beyond screens.

Growing pains

While <a href="https://www.techtimes.com/articles/309937/20250409/apple-vision-pros-sales-flop-theyre-rushing-out-new-one-m5-chip-before-2025-ends.htm" target="_blank" rel="noopener noreferrer">Apple Vision Pro has been a slow burner</a>, it’s still early days for spatial and multimodal UI design, but one thing is clear – the UI of tomorrow won’t live on screen. We’re moving into a new era where interfaces live around us, watching, listening, and responding as we interact with them and the world around us. And design systems won’t just be about aesthetics or branding; they’ll need to feel native and reactive to real-world environments, natural movement, and human behaviour.Liquid Glass is the start of a much bigger shift in design and how we interact with our devices. By introducing translucency, depth, and movement into today’s rectangular screen boundaries, it’s preparing us all for a world where interfaces are responsive and immersive, and not restricted to a glass rectangle.Brands that embrace multimodal, spatial design languages now will be the ones who lead in the years ahead as our digital and physical worlds blend together. And users will expect that to feel natural. As for designers and developers, those of us who understand this early and adopt this design ethos will define what’s coming next.

The UI of tomorrow won’t live on screen

Why you’re looking at Apple’s Liquid Glass UI the wrong way

Our new Pantone guides have arrived

We’ve already raided these ahead of Easter…

We’ve already raided these ahead of Easter…

It’s not too early for a Creme Egg, right?

We’re back in the swing of things after Christmas and New Year. Check out what we’ve been up to this month 🎞️

We’re back in the swing of things after Christmas and New Year. Check out what we’ve been up to this month 🎞️

January Wrapped 📸

We’ve been tidying up the office the last couple of weeks and found a few retro devices in the cupboards. A total throwback for a lot of us. We used to test on these devices back in the day!

We’ve been tidying up the office the last couple of weeks and found a few retro devices in the cupboards. A total throwback for a lot of us. We used to test on these devices back in the day!

We woke up in the 00’s today 📞 

We were at Shaping Portsmouth 2026 on Friday, listening to some genuinely inspiring people talk about the future of our city. Plus, Steve got his moment in the spotlight 🎤

We were at Shaping Portsmouth 2026 on Friday, listening to some genuinely inspiring people talk about the future of our city. Plus, Steve got his moment in the spotlight 🎤

Conference day ✨

Safe to say they didn't last long.

Love it when surprise biscuits show up at the office 🍪

There's something satisfying about cracking open fresh colour swatches for a brand project. These new guides are helping us lock down the perfect palette for a client who's going through a complete rebrand. The best part of a brand job? Getting to build brands from the ground up.

There's something satisfying about cracking open fresh colour swatches for a brand project. These new guides are helping us lock down the perfect palette for a client who's going through a complete rebrand. The best part of a brand job? Getting to build brands from the ground up.

Fresh Pantone guides just landed on the desk 🎨

It’s nearly Christmas, and as we shut down for the festivities, we thought we’d share some of our favourite moments from 2025. Have a merry Christmas and a happy New Year! See you all in 2026 🎉

It’s nearly Christmas, and as we shut down for the festivities, we thought we’d share some of our favourite moments from 2025. Have a merry Christmas and a happy New Year! See you all in 2026 🎉

December Wrap-Up 📸 

It’s been a busy one with projects kicking off, conferences, and so much more…

It’s been a busy one with projects kicking off, conferences, and so much more…

November Wrap-Up 📸 

It’s always good to get some time away from the office (and learn some new things along the way). Already looking forward to next year 👀

It’s always good to get some time away from the office (and learn some new things along the way). Already looking forward to next year 👀

⏱️ We had a great day Agency Hackers Clockwork conference at the British Library. 

🍔 A little pub lunch (we love a steak sandwich), a modded iPod that’s giving serious design nostalgia, and a (slightly less nostalgic) drone. And lots more in between…

🍔 A little pub lunch (we love a steak sandwich), a modded iPod that’s giving serious design nostalgia, and a (slightly less nostalgic) drone. And lots more in between…

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