The outline-width property is used in CSS and certain HTML elements. It specifies the thickness of the outline around the selected object, rendering each side the same as the others.

Values

• thin - Typically 1px in desktop browsers.
• medium - Typically 3px in desktop browsers.
• thick - Typically 5px in desktop browsers.
• <length> - A unit of measurement. Ex. px, pt, em, etc.

HTML example:

<span style="outline:solid medium;">Outline this text</span>

That produces: Outline this text

CSS example:

h1 {
    outline: solid medium;
}