Responsive design changes the arrangement when the available space changes. A media query can stack a sidebar above content, but many elements only need a fluid width with a sensible maximum. Keep those two techniques distinct. A fixed 480px card still overflows a narrow phone even if it looks fine on desktop. Images also need an automatic height when their width changes, or the illustration stretches. You'll check both desktop and phone boxes in the preview. Preserve the reading order across those widths. Reversing the visual order while leaving keyboard and source order unchanged creates an interface that is harder to follow.