Hi! You can make your site appear differently in different sizes by adding a rule like this to your css:
@media (max-width : 1920px){
}
... and changing the pixel amount to whatever size you like! For example, on my site I have all of my desktop specifications inside a 1920px rule, and all of my mobile specifications inside a 750px rule.
Just put all your selectors that you want to differ between sizes under each rule, and change the properties accordindly. For example, on my site I have this code:
@media (max-width : 1920px){
#navigation {
display: block;
}
#mobilenav{
display: none;
}
}
@media (max-width:750px) {
#navigation {
display: none;
}
#mobilenav {
display: block flex;
}
}
My navigation bar is in a vertical format in desktop, and a horizontal format in mobile, so I have the vertical one set to appear and the smaller one to disappear on larger displays - and vice versa.
Some other things that are helpful to have change between display sizes: box width, text size, the % of space an image takes up, and so on. It's helpful to check out sites you like on a mobile phone to see how they do things, too