A border provides a frame for your boxes. In this module find out how to change the size, style and color of borders using CSS.
In the box model module, we considered a frame analogy to describe each section of the box model.
The border box is the frame of your boxes, and the
border properties give you a huge array of options to create that frame in nearly any style that you can think of.
Border properties #
border properties provide a way to style the various parts of a border.
For a border to appear, you have to define the
border-style. There's a few options to choose from:
When using the
groove styles, the browser will darken the border color for the second shown color to provide contrast and depth. This behaviour can vary between browsers, especially for dark colors such as
black. In Chrome, these border styles will appear to be solid and in Firefox, they will be lightened to then provide a darker second color.
Browser behaviour can vary for other border styles too, so it's important to test your site in different browsers. A common example of this difference is how each browser renders the
padding, you can use the
border shorthand property to define all the parts of your border in one declaration.
border: 1px solid red;
The order of values in the
border shorthand are
border-style and then,
You can set color on all sides of your box or on each individual side with
border-color. By default, it uses the box's current text color:
currentColor. This means that if you only declare border properties, like width, the color will be that computed value unless you explicitly set it.
border: solid; /* Will be a blue border */
border: solid yellow;
The width of a border is how thick the line is, and is controlled by
border-width. The default border width is
medium. This won't be visible unless you define a style, though. You can use other named widths such as
border-width properties also accept a length unit such as
%. To set border width on each side of your box, use
Logical properties #
In the Logical Properties module you discovered how to refer to block flow and inline flow, rather than explicit top, right, bottom or left sides.
You have this capability with borders, too:
border: 2px dotted;
border-inline-end: 2px solid red;
In this example,
.my-element has all sides defined as having a
2px, dotted border that is the current text color. The
inline-end border is then defined as
2px, solid and red. This means that in left-to-right languages—like English— the red border will be on the right side of the box. In right-to-left languages—like Arabic— the red border will be on the left side of the box.
Browser support is varied for logical properties in borders, so make sure you check support before using.
Border radius #
To give a box rounded corners use the
This shorthand adds a consistent border to each corner of your box. As with the other border properties, you can define the border radius for each side with
You can also specify each corner's radius in the shorthand, which follows the order: top left, top right, bottom right then bottom left.
border-radius: 1em 2em 3em 4em;
By defining a single value for a corner, you are using another shorthand because a border radius is split into two parts: the vertical and horizontal sides. This means that when you set
border-top-left-radius: 1em, you are setting the top-left-top radius and the top-left-left radius.
You can define both properties, per corner like this:
border-top-left-radius: 1em 2em;
This adds a
border-top-left-top value of
1em, and a border top-left-left value of
2em. This converts the top left border radius into an elliptical radius, rather than the default circular radius.
You can define these values in the
border-radius shorthand, using a
/ to define the elliptical values, after the standard values. This enables you to get creative and make some complex shapes.
border: 2px solid;
border-radius: 95px 155px 148px 103px / 48px 95px 130px 203px;
Border images #
You don't just have to use a stroke-based border in CSS. You can also use any type of image, using
border-image. This shorthand property allows you to set the source image, how that image is sliced, the image width, how far the border is outset from the edge and how it should repeat.
border-image-slice: 61 58 51 48;
border-image-width: 20px 20px 20px 20px;
border-image-outset: 0px 0px 0px 0px;
border-image-repeat: stretch stretch;
border-image-width property is like
border-width: it is how you set the width of your border image. The
border-image-outset property lets you set the distance between your border image and the box that it wraps around.
border-image-source (source of the border image) can be a
url for any valid image, which includes CSS gradients.
border-image-source: linear-gradient(to bottom, #000, #fff);
border-image-slice property is a useful property that allows you to slice an image into 9 parts, made up of 4 split lines. It works like the
margin shorthand where you define the top, right, bottom and left offset value.
border-image-slice: 61 58 51 48;
With the offset values defined, you now have 9 sections of the image: 4 corners, 4 edges and a middle section. The corners are applied to the corners of the element with the border image. The edges are applied to the edges of that element. The
border-image-repeat property defines how those edges fill their space and the
border-image-width property controls the size of the slices.
fill keyword determines whether the middle section, left by the slicing, is used as the element's background image or not.
border-image-repeat is how you instruct CSS how you would like your border image to repeat. It works the same as
- The initial value is
stretch, which stretches the source image to fill available space where possible.
repeatvalue tiles the source image's edges as many times as possible, and may clip the edge regions to achieve this.
roundvalue is the same as repeat, but instead of clipping the image edge regions to fit as many as possible, it stretches the image as well as repeating it to achieve a seamless repeat
spacevalue is again, the same as repeat, but this value adds space between each edge region to create a seamless pattern.
Which is the default border color?
This special CSS value will represent the computed
text-color value, and is the default border color.
This is made up. Try again!
border: solid hotpink;
What is the default width of a border?
This is a
border-style value, not a
put borders on the left and right (in Latin layouts). put borders on the top and bottom (in Latin layouts). put borders on the inside. put borders on the first line.
border-inline: 1px solid would...
In a Latin layout like English,
border-block would be the top and bottom.