CSS border

<!doctype html>
<title>Example</title>
<style>
div {
  font-size: 1.5em;
  padding: 20px;
  border: 9px solid orange;
  }
</style>
<div>This 'div' is styled using the CSS border property. Try changing the values to see the effect it has on the border of the div.</div>

The CSS border property is shorthand for setting all styles on the borders of an element.

The border property is a shorthand property for the border-width, border-style, and border-color properties.

If you need to apply a different style to each border, you will need to use one of the other, more specific, border properties (for example, border-top, border-top-color, border-style, etc)

Syntax

Where

And

These values are explained below.

Possible Values

line-width

This sets the border-width property. Possible values are:

thin: Specifies a thin border. It is up to the user agent to determine the actual width.
medium: Specifies a medium width border. It is up to the user agent to determine the actual width.
thick: Specifies a thick border. It is up to the user agent to determine the actual width.
length: Specifies the width of the border using a length value. For example, 10px, 1em, 8pt etc

line-style

This sets the border-style property. Possible values are:

none: No border. Color and width are ignored. Therefore, the border's width is 0, and the initial value of border-image-width will also resolve to zero.

Note that when using the collapsing border model (border-collapsed tables), a none value may not always appear to work, due to another element having a non-none value. This is because multiple elements can share the same edge in border-collapsed tables. For example, a table, tbody, tr, and td could all share the same edge and have different border settings.

To completely turn the border off, either make all elements that share that edge none, or use hidden on any of the elements that share that edge.
hidden: Same as none, but in the collapsing border model (border-collapsed tables), also inhibits any other border. In other words, when multiple edges come together with different border settings (for example, a table and a td, each with their own border settings), if any one of those is hidden, it will prevent any border at that edge. This is different to none, in that all elements meeting that edge must have none before the border is omitted.
dotted: A series of round dots.
dashed: A series of square-ended dashes.
solid: A single line segment.
double: Two parallel solid lines with some space between them. When using this value, the border-width value determines the sum of the lines and the space between them.
groove: Looks as if it were carved in the canvas.
ridge: Looks as if it were coming out of the canvas.
inset: Looks as if the content on the inside of the border is sunken into the canvas. Treated as ridge in the collapsing border model.
outset: Looks as if the content on the inside of the border is coming out of the canvas. Treated as groove in the collapsing border model.

color

This sets the border-color property, which specifies the color of the border. It must be a valid color.

In addition, all CSS properties also accept the following CSS-wide keyword values as the sole component of their property value:

initial: Represents the value specified as the property's initial value.
inherit: Represents the computed value of the property on the element's parent.
unset: This value acts as either inherit or 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.

General Information

Initial Value

This is based on the individual properties' values. Their initial values are as follows:

border-width: medium
border-style: none
border-color: Uses the currentColor value (which is the value of the color property).

Applies To

All elements.

Inherited?

Media

Visual

Animatable

Yes, as the individual properties (see example)

Example Code

Official Specifications

CSS Backgrounds and Borders Module Level 3 (W3C Candidate Recommendation 9 September 2014)
CSS Level 2.1 (W3C Recommendation 07 June 2011)
CSS Level 1 (W3C Recommendation 17 Dec 1996)