Cross-browser testing: making sure the site works for everyone
A site that looks perfect on the developer's laptop can break on a budget Android with a three-year-old browser — and that is a meaningful share of your audience.
Why rendering differs
Browsers use different engines, adopt new CSS and JavaScript features at different times, and handle errors differently. What one engine forgives, another renders wrong or not at all.
Safari on iPhone is its own case: it lags on newer features and behaves distinctly around viewport height, form fields and video, which is where most 'everything is shifted' reports come from.
What to actually test
Start from data, not guesses: analytics shows which browsers, devices and resolutions your audience actually uses.
A practical minimum here: current Chrome on Android, Safari across a few iPhone generations, desktop browsers, and Telegram's in-app browser — a substantial share of traffic arrives through messenger links and that webview behaves differently.
What breaks most often
Horizontal scrolling from an over-wide element, layout shifting when a form field is focused on iOS, custom dropdowns, and buttons made unclickable by overlapping layers.
Autoplaying video is its own category: policies differ per browser, and a background video on desktop can be a black rectangle on mobile. Always set a poster frame as fallback.