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Notes on testing the web on every screen.
Guides, references and honest comparisons for responsive design, accessibility, performance and launch images.
GuideHow to test responsive design on multiple devices at onceA practical workflow for checking a website on phones, tablets and laptops at the same time: which sizes to pick, what to check and which tools help.
GuideHow to find the breakpoints of any websiteThree ways to list the media query breakpoints of a page: DevTools, a console snippet that reads every stylesheet, and a tool that does it for you.
GuideChrome DevTools device mode: 6 things it doesn't show youDevice mode is a great start, but it shows one viewport at a time and skips several things real phones do. Here is what it misses and how to cover it.
ToolsResponsive design testing tools in 2026: an honest listFrom free built-in browser tools to dedicated multi-device browsers and real-device clouds: what each kind of responsive testing tool is good for.
ReferenceViewport sizes for iPhone, Android, iPad and laptops (2026)CSS viewport widths, heights and device pixel ratios of current iPhones, Android phones, foldables, tablets and laptops, in one table.
CSSHow to find what causes horizontal scroll on mobileA page that scrolls sideways on phones almost always has one element wider than the viewport. Here is how to find it fast, and the usual culprits.
AccessibilityHow to test color contrast against WCAG 2.2The contrast ratios WCAG requires for text and interface parts, how the ratio is calculated, the cases tools miss, and how to check a whole page.
GuideHow to make device mockup screenshots of your websiteTurn your live website into launch images: phones, tablets and laptops in device frames, on a background, with a headline and callouts, without a design tool.
GuideHow to take a full-page screenshot in ChromeCapture a whole web page, not just what fits on screen: the built-in DevTools command, the problems with long pages, and capturing every device size at once.Test every screen before your users do.
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