first mobile-solution using CSS flexbox.

Hi, if you want to set different styles on different screen size you have to use media queries.

To do this you can wrap all your styles in:

@media (max-width: 400px) {
***your styles***
}

It means that all of your styling will be applied until page width crosses 400px.

So you can copy all your styles twice. One for @media (max-width: 400px) {} and one for @media (min-width: 401px) {} and then just style it for desktop. In that the changes won't be applied for Mobile View.

And about responsiveness I have one advice: Avoid hard height and width settings of the elements unless you really have to do it. Pages are responsive by default. But if you have to do it temporarly, use max-width or min-width instead of width. Same rule for height. And try to set it with vw and vh instead of px.

vw is ViewportWidth (100vw means it will always have width equal to page width). vh is ViewportHeight (100vh means it will always have height equal to page height).

Good luck!

You need to use Media Queries for that. You use Media queries to determine how the page is going to behave in a determinate size. But you have to code every possible screen size you want to add.

The one you've done now should be inside a media query with a width of 400px or so. You just need to code the desktop version now. Remember that the desktop version comes first in the Cascade, and the mobile version comes after.