WCAG 1.4.10: Reflow
WCAG 1.4.10 Reflow is a level AA success criterion from WCAG 2.1. At 320 CSS pixels wide, content should reflow without horizontal scrolling, except for things that need two dimensions such as maps and tables.
People zoomed in on a phone should not have to scroll sideways to find the price.
How to test
Set the browser to 320 pixels wide. Scroll the product page. Only a data table may scroll sideways.
How to fix
Use wrapping layouts. Avoid fixed widths wider than the screen.
Example that fails
A hero row stays 960 pixels wide and the buy button is off to the right.
Example that passes the check
At 320 pixels the title, price and button stack.
Shopify
Test the theme at 320 pixels. Fix sections that set a min-width on the product row.
WooCommerce
Override fixed widths in the theme CSS so the product summary stacks.
WordPress
Avoid wide blocks that do not wrap. Set images to max-width 100 percent.
Wix
Check the mobile editor at a narrow width and stack strips that overflow.