Orientation
Content must not be locked to a single display orientation (portrait or landscape) unless a specific orientation is essential.
What it requires
WCAG 2.1 SC 1.3.4 prohibits orientation-locked websites. Mobile users with mounted devices (wheelchair tablets, mounted phones) cannot rotate their hardware; web content that forces portrait-only or landscape-only is inaccessible.
Only essential orientations are exempt — bank-check imaging, piano keyboards, virtual reality. Ecommerce content has no essential-orientation exemption.
Common Shopify failure
Mobile-only theme that uses `screen.orientation.lock('portrait')` in JavaScript. CSS `@media (orientation: portrait)` rules that hide critical content in landscape. Custom video-player overlays that block landscape rotation.
How to fix it
Remove `screen.orientation.lock` calls. Replace orientation-only CSS rules with viewport-width media queries (`@media (max-width: <breakpoint>)`).
Primary source: W3C — WCAG 2.1 Understanding 1.3.4