I don't want my outline to have rounded corners, but it becomes rounded while it is getting wider during the animation.
Edit: I'm getting the following appearance in Linux, MS Edge, and looking at your reaction I tried it on Mozilla Firefox, it seems working perfectly that is however I want. But for those who may use MS Edge, is there a solution to apply?
.btn {
width: 20%;
height: 15%;
font-size: larger;
border: none;
background-color: darkgrey;
transition: outline-offset 1s;
}
.btn.border-pop:hover {
outline: solid darkgrey;
outline-offset: 10px;
}