Why it matters
Disabling zoom locks out everyone who needs to magnify text. On modern browsers it buys nothing in return.
How to fix it
Remove user-scalable=no and any maximum-scale below 2 from the viewport meta tag.
Users can zoom the page
Low impact · weight 4 · worth up to 1.7 points of the total score
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More Markup checks
No deprecated presentational tags
Tags like <center> and <font> were removed from the standard. Browsers still honour them today, but they mix styling into the markup and no longer respond to CSS the way the rest of the page does.
Page declares a favicon
The favicon is how a user finds this tab among twenty others and how the site appears in bookmarks and history. Without a declared one the browser requests /favicon.ico and usually gets a 404.
Styling lives in stylesheets, not attributes
Inline style attributes cannot be cached, overridden by a stylesheet, or covered by a Content Security Policy that forbids inline styles. In quantity they also bloat every HTML response.
Viewport meta tag is present
Without it mobile browsers render the page at desktop width and shrink it to fit, which fails Google's mobile usability bar and leaves text unreadable on a phone.