Pixels are static values which may work for certain dimensions but will cause problems and hinder design at different dimensions/views(mobile-desktop) For responsive web design it is a must to follow certain design practices : 1- No Pinch Zoom: Solved by applying viewport correctly. 2- No Horizontal Scrolling: Solved by using relative sizing and positioning and instead of absolute positioning. 3- Font-size Handling: Use em and rems instead of pixels. 4- Layout: Use Media Queries,Flexboxes, Bootstrap etc.