2 different design for computer, and for mobile

I couldn’t get the code that I have to put in order to do what I wanted

So here’s an example:

https://jsfiddle.net/qzaL8719/

You have to resize the window to see what is happening. Always design mobile first.

Also., I highly recommend using these media queries:

min: 320px <-- not needed as a media query., but begin your design at this size. It’s for iphone4.
tablet: 728px
desktop: 1366px

I’ve created several sites, and these 3 cover most of your situations.