outline-width property is used to specify the width of an element's outline.
Unlike an element's border (e.g. set using
border or its associated properties), an element's outline does not take up extra space and it can be non-rectangular.
The outline is always on top of a box, and it does not influence the position or size of the box, or of any other boxes. Therefore, displaying or suppressing outlines does not cause reflow or overflow.
User agents typically render an outline on elements in the
These values are explained below.
- Allows you to specify a non-negative length value as the outline's thickness. Negative values are invalid.
- Specifies a thin outline, as determined by the user agent.
- Specifies an outline of medium thickness, as determined by the user agent.
- Specifies a thick outline, as determined by the user agent.
In addition, all CSS properties also accept the following CSS-wide keyword values as the sole component of their property value:
- Represents the value specified as the property's initial value.
- Represents the computed value of the property on the element's parent.
- This value acts as either
initial, depending on whether the property is inherited or not. In other words, it sets all properties to their parent value if they are inheritable or to their initial value if not inheritable.
- Initial Value
- Applies To
- All elements
The CSS spec warns against removing the outline on elements in the
Keyboard users, in particular people with disabilities who may not be able to interact with the page in any other fashion, depend on the outline being visible on elements in the
:focusstate, thus authors must not make the outline invisible on such elements without making sure an alternative highlighting mechanism is provided.
- CSS Basic User Interface Module Level 3 (CSS3 UI) (W3C Candidate Recommendation, 02 March 2017)
- CSS Level 2.1 (W3C Recommendation 07 June 2011)