11.2. Ensure content readability even when font size is doubled
Guarantee content readability even when font is twice the default size.
Across the entire font size increase range, content and functionalities must not overlap or disappear.
To ensure this rule is respected:
- Use only relative units (
rem
,em
,%
, etc.) to manage spaces (CSS propertiesmargin
andpadding
). - It is not recommended to use units (
px
,pt
,em
,%
, etc.) with theline-height
CSS property. - It is not recommended to define a fixed height (CSS
height
property) on elements likely to contain text, particularly form fields. - Be careful when using absolute positioning (CSS declaration:
position: absolute;
). Although this type of positioning is compatible with accessibility, it can cause content overlap in some cases.