The outline of a box is almost the same as the border.
The outline is not actually a part of the box, it does not count in any way towards the width or height of a box.
Its syntax is the same as for the border: width, style and
color. Unlike a border, adding special instructions for one side of the
outline (like outline-left-width) is not possible. You can define only a complete outline
around the entire element.
p.test {
outline: 3px solid #6374AB;
border: 1px solid #000000;
width: 20em;
}
<p class="test">