Yes, border and outline look quite similar at first look. However, these two properties behave completely different, although users outline often mistake for a border. Even their syntax looks almost identical if you look at it:
Let’s discuss this more in detail, and see what are borders and outlines, and what are the differences between them.
What are Border and Outline?
The CSS Border property defines the width, line style, and color of the border of an HTML element. On the other hand, CSS Outline property specifies the line drawn around an HTML element, outside of the border.
With that being said, the most simple way to distinguish borders and outlines is to remember borders as a part of a HTML element, while the outline is a space around that element.
Main Differences between Border and Outline
Borders influence the element size and impact surrounding elements, while the outlines do not do that.
This is the most important difference between the two.
Borders are a part of the box model. This means that the border is considered as the part of an element’s box, and it actually occupies the space around the element. So, any change in size of the border will influence the surrounding elements.
Unlike a border, an outline does not occupy the space. It is actually placed on top of the element’s box, and surrounds the border. Outlines are drawn outside the borders. If we change the size of an outline and make it larger, it will not push surrounding elements, but it will overlap them.
Borders do allow changes on individual sides, while the outlines behave as the whole.
You can style borders on each side differently. For instance, we can color the top border in green, while the bottom border is red and thicker.
This kind of customization is not possible when we look at the outline. Outline acts as one, so you can not change the styling of the edges.
Outlines do not support round corners, while you can get that with borders.
Borders have a border-radius property, which allows us to have nice, round corners around our elements, This styling method is often used on buttons.
Outline on the other hand, does not support such property.
Why do we want to use Outlines?
Well, outlines are extremely useful from a styling point of view.
With outlines, we define the outside area of an element, which can be quite helpful if we want our element to stand out from surrounding elements.
In addition, outline has a great choice of different styles. This allows us to achieve the desired look in a much easier way, than it would be with border manipulation and using a box-shadow property.
Understanding difference between border and outline will give you better control over your webpage design and elements’ appearance.
The CSS Border property defines the styling of a border of an HTML element. On the other hand, CSS Outline property determines the line drawn around an HTML element. This refers to a space outside of the border.
If you wish to learn more about CSS and why CSS is important language to understand, you can read it in the article What is CSS and why is CSS so important?