The outline is a line around the elements. It is the part of OUTSIDE the borders. The outline property is used to make the element stand out.
CSS has the following outline properties:
{outline-color : orange;}
property value
<!DOCTYPE html>
<html>
<body>
<p style="outline-style:orange;">
TDB Tutorials
</p>
</body>
</html>
If we want to change the style of the outline of an HTML element we can use the CSS3 outline style Property.
{outline-style : solid;}
property value
<!DOCTYPE html>
<html>
<head>
<style>
.tdb-school{
background-color:white;
padding:10px 35px;
border-style:dotted;
border-radius:5px}
</style>
</head>
<!--Body-->
<body>
<button type="submit" class="tdb-school">
button border properties
</button>
</body>
</html>
If you don't want to write different CSS rules for Outline property then you can use Outline Shorthand property.
{outline : color style width}
property value
<!DOCTYPE html>
<html>
<!--Body-->
<body>
<button type="submit" class="tdb-school"
style="outline:orange dotted 5px;
padding:10px 35px;border:solid red 5px">
button outline property
</button>
</body>
</html>