The viewport is the part of the browser window in which your page's content is visible. When your page's content width is smaller or larger than the viewport width, it may not render correctly on mobile screens. For example, if the content width is too large, content may be scaled down to fit, making text difficult to read.
How the Lighthouse content width audit fails
Lighthouse flags pages whose width isn't equal to the width of the viewport:
The audit fails if window.innerWidth does not equal window.outerWidth.
How to make your page fit on mobile screens
This audit is a roundabout way of determining if your page is optimized for mobile devices. See Google's Responsive Web Design Basics for an overview of how to create a mobile-friendly page.
You can ignore this audit if:
- Your site does not need to be optimized for mobile screens.
- The content width of your page is intentionally smaller or larger than the viewport width.