Mobile first using Sass - feedback me, please

You have to add the transition on both instances. Let's you have a div that's a square and you want it to expand when you hover over it;

div {
width:200px;
height:200px;
background: red;
transition: 0.3s
&:hover{
width:300px;
height: 300px;
transition: 0.3s;
}}

That's how you supposed to do it, the transition must be on both of them.

& There is something that is giving you a horizontal scroll, am not sure what it is but you should check it out.

Keep coding👍.