The outline property is a shorthand property for outline-width, outline-style, and outline-color.
An outline is a line rendered around and outside the borders of an element to make it stand out. The outline-style value is required. If outline-color is not specified the outline will be the same color as the text.
h3.ex {
outline: 2px solid #000;
}outline-width
Sets the width of the outline.
outline-style
Sets the style of the outline.
outline-color
Sets the color of the outline.
initial
Sets the property to its default value.
inherit
Inherits this property’s value from its parent item.
User-submitted codepen.io examples of outline ↴
Submit a codepen.io link that demonstrates outline: