Designing websites for smartphones is easy compared to retrofitting those already in place. More than that, it’s embarrassing how, almost eight years after CSS gained practical acceptance, a lack of foresight haunts those of us who write HTML.
Converting older websites to responsive design causes headaches not because small screens are difficult, but because most HTML documents were written under an assumption about screen size. Prior to the iPhone’s introduction in mid-2007, designers could rely on windows at least 700 pixels wide (if they ignored accessibility). Conventions like navigation bars, two- and three-column layout and hover effects evolved to fit the mouse-based wide-screen standard. Designers made their upper left corner logos clickable because it was expected.