Another way to do it, is to duplicate your content blocks and then hide / show the ones you want using display: none;
Example: You have a block that you want one step lower on mobile. Duplicate it, put it where it would be on mobile, then hide it on the desktop version, but leave it visible on the mobile version vice versa.
You can use "@media only screen and (max-width:768px) { your CSS here }" to change stuff only on mobile devices.
This method will affect your page load time tho. It might also affect your SEO if you duplicate stuff that contains h1 tags or image alt data.