Design for reflow
Columns should stack logically, text should remain readable and controls should not force horizontal scrolling. Responsive behaviour should be planned component by component.
Navigation needs deliberate mobile behaviour
Large desktop menus often need a simpler mobile pattern. Dropdowns must remain keyboard- and touch-friendly, and opening the menu should not trap or hide important content.
Images need the right dimensions
Serving oversized imagery wastes bandwidth. Use appropriate formats, responsive sizing and sensible compression while preserving the visual quality the design requires.
Forms deserve mobile testing
Input types, labels, error messages, button sizes and spacing affect completion. Test forms on real narrow screens, not only by shrinking a desktop browser.
Prioritize the content people need on the move
Phone users may be looking for directions, hours, a quote, a booking or a quick service answer. Do not hide essential information simply because the screen is smaller.
Design important components at several widths
Do not create one desktop mockup and leave mobile behaviour to the developer. Decide how navigation, service cards, pricing tables, galleries and multi-column sections should reflow. Tablet widths often expose problems that are not obvious at desktop or phone extremes.
Touch changes interaction design
Hover-only information does not translate well to touchscreens. Controls need spacing, dropdowns need predictable tap behaviour and important actions should not depend on precise pointer movement. Responsive design includes interaction, not only dimensions.
Test content extremes
Try long headings, validation errors, enlarged text and unusually long navigation labels. Components that look perfect with short placeholder copy can break when real content arrives. Testing realistic extremes makes the design more resilient.