Guides
In-depth guides
Longer walkthroughs for specific setups: real screenshots, code you can paste and the reason behind every step. The short fix page for each check lives under Learn.
All guides
30 guides, page 3 of 3.
- Best practices11 min read
Responsive web design: what it is, how it works, and responsive vs adaptive
Responsive web design is one page whose layout adapts to every screen with CSS. How it works, the layout patterns with examples, how it compares with adaptive design and separate mobile sites, and how to test it.Updated 26 Sept 2026 - Best practices11 min read
Console errors and deprecated APIs: what the report flags
What the console errors, deprecated APIs and document.write findings mean, where the errors usually come from, and how to reproduce and fix each one, with code for the common cases.Updated 25 Sept 2026 - Best practices11 min read
Custom 404 pages that help: status codes, content and the check
A good 404 page keeps the visitor on your site and tells search engines the page is gone. What to put on it, how to make sure it returns a real 404, and how getReport tests yours with a random URL.Updated 25 Sept 2026 - Best practices14 min read
GA4 and Tag Manager: what they cost your page and how to load them
See what GA4 and Google Tag Manager cost your page in bytes and main-thread time, the loading options ranked by cost, Consent Mode v2 defaults in code, and a container clean-up list.Updated 25 Sept 2026 - Best practices11 min read
HTML validation errors: which ones matter and which are noise
A validator can list 200 errors on a page that works. Learn the handful that change how browsers, screen readers and Google read the page, how to find them, and which ones you can safely ignore.Updated 25 Sept 2026 - Best practices11 min read
Privacy policy and contact links: the trust signals a report checks
What the privacy policy and contact checks look for, what a small site's privacy policy and contact page should contain, where to link them, and how to keep the policy in line with your cookies.Updated 25 Sept 2026
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