Yes it is. Except you can't use the same markup for both because the input devices, and thus interaction paradigms, are so radically different. Mice are precise and capable of hovering over things, so it makes sense to pack everything densely and add various tooltips and popup menus. Touchscreens are imprecise and don't have anything resembling hovering, so UI elements must be large, with enough padding around them, and with menus appearing on click.
Between CSS Flexbox and CSS Grid there shouldn't any reasons today that you can't handle 100% of those differences with the same markup and media stylesheets. (There's also obviously JS if you really must contort the HTML DOM to get what you want.)
