Visitors on your website use a wide variety of devices and screen sizes. It's important to plan the site's design for all of these to retain a great user experience. What might look great on the designer's 27" 5k screen might not fit as well on a visitor's 13" 1280x800 notebook. The way each block or blade of content is designed should cater to these, and other sizes either by how they're defined to behave or by using CSS breakpoints to deliver that same element with different styling.
We have much more than a simple list of devices to design for. Smartphones come in a variety of sizes as do tablets. Desktop and notebook users may not always view your site at 100% screen size, especially on an OS that lets you snap a site to the left or right of the screen. Tablet users may use the device in landscape or portrait. During the design process, it's important to plan for all of these viewports to ensure the site works and looks great across the board.
Big images are great, but how much of the screen do they take up on a shorter display like a tablet or small notebook? If text is positioned in a specific spot on top of a hero image or slideshow, can it still fit if the image is smaller or shorter? These are things that are important to consider when building out the initial design to make sure things can be resized to responsively fit in different environments.
A simple way to plan for responsive when building a desktop sized comp is to consider how things will resize at less than your Photoshop art board. Does the left and right of the image get cut off if the image is at a fixed height, and is that still ok? If the height is a percentage retaining the original ratio of the image to avoid any cropping of the image, can the associated text on top of the image still fit and be readable?
Blocks of content should either be able to resize to fit different environments based on percentages, while retaining their readability. If at any point, like on a smartphone, the percentage widths of an element make it unreadable, a CSS breakpoint should be change the element to best fit in that particular size. Example: You may have four columns of content showcasing a list of top clients in your desktop comp. Four columns of text may not fit well on a smartphone, so the breakpoint will adjust the layout at these sizes to show the same content stacked in one column rather than side by side in four. Planning for this breakpoint in the design process with a comp helps ensure the site is true to the designer's vision while making sure it looks and works great in every environment.
Ask the client what device they use to make sure when they view the comps it looks great on their specific screen.
Many times, seeing display issues in a comp is as simple as viewing the design at 100% within the browser on a particular device. If a client's primary computer is a smaller notebook, and they look at the comp at 100% in their own browser (which may have a shorter height with tabs and bookmarks bar), it's easier to notice things like "Why can't I see this content above the fold?" or "This image is too tall for my screen.". Delivering a 100% JPG or PNG comp for review which can be viewed within the actual viewing environment can showcase precisely what the end result will be. A PDF or image viewed at sizes other than 100%, or worse - printed out on paper, can't accurately show what the final product will look in a browser.
In most cases, two breakpoints can be enough: mobile (smartphones and tablet portrait) and desktop (tablet landscape and notebook/desktop). These two sizes fall into ranges of pixel sizes:
- Desktop: 1024px - 1200px and beyond
- Tablet: 768px - 1024px or < 1024px
- Phone: < 768px (optional)
Setting a unique style for phone is optional as in many cases, tablet in portrait mode may look the same as on phone. Other breakpoints may take into account the device height too. A notebook might have a 1366px wide screen, but it's important to consider they only have 768px (minus the browser frame, tab and bookmarks bar, dock, etc) viewing height before scrolling.
Breakpoints should cascade from desktop down to smaller devices since we make adjustments from the larger size to fit on smaller screens.
"Mobile first" isn't always the best approach, especially if the design we're starting from are designed for a desktop browser. CSS means "Cascading Style Sheet", which means style declarations will cascade from top to bottom. Build your CSS for desktop then include your responsive edits to the original styles at the end, which will retain the desktop style for anything not overwritten for the other breakpoints. I like to keep my main CSS in a separate file from the responsive CSS to keep things tidy. In most cases, the responsive adjustments I make for extra large or smaller mobile sizes is relatively short. Keeping them separate is a tidy way of making things easy to locate.
Alternate Elements for Specific Viewports
Oftentimes, a multi-column layout works fine on desktop but has to be structured differently to fit on a mobile sized device. For example, we may have 2 columns with text on the left and 2 images on the right. On mobile, the default assumption would be "stack left column on top of right column", but in this case might not look as good. For this, I set a .mobile-only and .desktop-only CSS class that sets display: none; to completely hide an element in a breakpoint. This way, I can have a desktop version of the block HTML duplicated for mobile in the code, yet only one shows up on desktop and the other on mobile.
- Browser Display Statistics - important to note that screen resolution does not mean the user's browser is full screen. People with larger screens can see content side by side in multiple windows, so actual browser size will usually be less than screen resolution, and height will always be shorter than screen resolution.