2026-09-08 · 6 min read · Rahul Chitturi
- css
- rtl
- internationalization
A layout written only with left, right, width, and horizontal assumptions can reverse incorrectly in right-to-left interfaces or vertical writing modes. The text direction may change while margins, borders, positioning, and icons remain physically anchored.
Logical CSS properties describe block and inline flow instead of assuming one screen direction. They help one component adapt, but only when direction and writing mode are set at the correct boundary.
Inspect the computed flow
Record the element's computed direction, writing-mode, inline axis, block axis, containing block, and inherited values. Test the actual localized document rather than simulating RTL with a transformed screenshot.
- Prefer margin-inline and padding-inline for flow spacing
- Use border-inline-start for directional emphasis
- Use inset-inline properties for positioned controls
- Keep physical properties when the requirement is truly physical
Resolve cascade and asset assumptions
A physical declaration can override a logical declaration depending on cascade order. Remove conflicting fallbacks where supported, or place compatibility rules in a deliberate order and verify computed styles.
Some icons should mirror, such as directional arrows, while logos, media controls, and many symbols should not. Keep icon semantics separate from text direction and include accessible labels.
Test the component in every flow
Use the CSS formatter to expose physical and logical declarations, diff for computed-style snapshots, units converter for sizing, color tool for state contrast, and HTML entities tool for safe bidirectional text fixtures.
Test LTR, RTL, vertical writing, mixed-direction text, long labels, zoom, keyboard focus, scrolling, overflow, positioned elements, animations, printing, and supported browser fallbacks.