Just a moment... | Gartner

When viewed on small screens (like mobile phones) content must fit without 
requiring scrolling in two dimensions.

WCAG 2.1 specifically requires this for:

+ Vertical scrolling content at a width equivalent to 320 CSS pixels
+ Horizontal scrolling content at a height equivalent to 256 CSS pixels

Except for parts of the content which require two-dimensional layout for usage or meaning,
such as a maps application.

Title / URL	Issues
Just a moment... \| Gartnerwww.gartner.com/invented-url-for-404-page	1
Just a moment... \| Gartnerwww.gartner.com/en/finance	1
Just a moment... \| Gartnerwww.gartner.com/en/insights/guides	1
Just a moment... \| Gartnerwww.gartner.com/en/legal-compliance	1

Ensure pages don't scroll in two dimensions on small screens

Gartner Inc

Where this issue has occurred