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CSS Outline: The Complete Guide To Stunning Web Design

Outlines in CSS allow developers to create visible borders around elements puwithout affecting the element’s box model. The outline property offers great design flexibility by controlling the style, width, and color of these borders.

The outline-style CSS property specifies the style of an element’s outline.

An outline refers to a line that is positioned outside of and surrounding an element’s border. Outlines serve primarily as decorative features to draw attention to a focused element, or to improve the accessibility of content by increasing its visibility or contrast against the background. Unlike borders, outlines do not take up space and do not alter the size or dimensions of the box element they encircle.

This article will provide a comprehensive guide to leveraging the outline property in CSS. By the end, you will have a solid grasp of how to leverage outlines creatively and effectively in your web designs and layouts.

CSS Outline Property

Outline is a CSS shorthand property that allows you to set most of the outline properties in a single declaration.

It includes outline-style for setting dotted, dashed, and double borders; outline-width for controlling thickness; and outline-color for applying color. In the later sections, we will cover the various values and use interactive examples to demonstrate visually how the outline adapts. Whether you want to highlight interactive elements, create offset borders, or apply other outline effects, this article will equip you with the key concepts and best practices for utilizing this underused yet powerful feature of CSS.

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The Outline-style Property

The following values are for the outline-style property. Each one gives a different visual appearance to the outline itself.

  • dotted – This value gives a dotted appearance to the outline.

  • dashed – This value provides a dashed look for the outline.

  • solid – When used, this value sets a solid line for the outline.

  • double – This value sets a double outline.

  • groove – When applied, this value gives a 3D groove to the outline.

  • ridge – Set a 3D ridged look for the outline.

  • inset – This value applies a 3D inset on the outline.

  • outset – A value used to provide a 3D outset outline.

  • none – This value states there is no outline, (the default).

  • hidden – This sets an outline but hides it on the HTML render.

The accompanying CSS example demonstrates the outline-style property applied to an element, with its value set to “double.” This produces a double-line effect for the outline border rendered around the element. Visually you can observe how using the double value for outline-style impacts the appearance of the outline, doubling the border. This gives an example of how the outline-style property can be leveraged to achieve different visual styles for outlines.

If you are new to CSS, check out this course about CSS for Absolute Beginners

body {
  background: #c387eb;
  padding: 0 24px;
  margin: 0;
  height: 100vh;
  color: white;
  display: flex;
  justify-content: center;
  align-items: center;
}

.box {
  width: 350px;
  height: 200px;
  outline-style: double;
  outline-color: white;
  outline-width: 8px;
  padding: 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

...
  <body>
    <div class="box">
      <h1>outline-style: double;</h1>
    </div>
  </body>

...

In this sample image, the CSS outline style is altered to the value of double.

The Outline-width Property

The outline-width property modifies the thickness of the outline border. Importantly, unlike standard borders, changing the outline width does not affect the element’s dimensions or space allotted in the document flow. Rather, it simply adjusts the visible thickness of the outline itself as rendered on the page.

Valid values for outline-width include common keywords like thin, medium, and thick, which produce preset width outlines. You can set this property using one of the following values:

  • thin – Sets a thin line for the outline, (default setting).

  • medium – Applies a medium line for the outline.

  • thick – This value sets a thick line on the outline, generally about 5 pixels.

  • User-declared size – You can set the size as you wish via px, in, cm, em, or pt values like 8px

In the example below, the outline-width property has been set to “thick” to alter its width.

.box {
  ...
  outline-width: thick;
  ...
}

...
<body>
  <div class="box">
    <h1>outline-width: thick;</h1>
  </div>
</body>
...

You can also set the outline-width to any value you want. For example, the outline-width has instead been set to a pixel size of 10 in the code snippet below ⬇:

.box {
  width: 350px;
  height: 200px;
  outline-style: double;
  outline-color: white;
  outline-width: 10px;
  padding: 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

The Outline-color Property

The outline-color property defines the hue applied to the outline, accepting various CSS color value types including hex codes, RGB/HSL values, and predefined color keywords. As demonstrated in the sample, setting outline-color to white changes the outline color surrounding the element to a white tone. Much like setting colors elsewhere in CSS, developers can leverage any valid color specification to modify the outline color as needed, whether that’s through hex values, rgb/hsla definitions, or basic color names supported in CSS. This flexibility enables customizable outline colors to complement designs.

.box {
  ...
  outline-color: white;
  ...
}

Additionally, the color value “invert” is available for outline-color. This applies an inverted color variant of the background behind the element, enhancing the visibility and contrast of the outline. Setting the outline-color to “invert” automatically determines a color that causes the outline to stand out prominently against the underlying backdrop, useful when needing the outline to remain noticeable regardless of varying background colors.

body {
  background: #ebaf87;
  padding: 0 24px;
  margin: 0;
  height: 100vh;
  color: rgb(51, 15, 15);
  display: flex;
  justify-content: center;
  align-items: center;
}

.box {
  width: 350px;
  height: 200px;
  outline-style: double;
  outline-color: invert;
  outline-width: 10px;
  padding: 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

...
<body>
  <div class="box">
    <h1>outline-color: invert;</h1>
  </div>
</body>
...

The Outline-offset Property

The outline-offset property introduces a gap between the element’s boundary and the outline, offering a useful feature to emphasize that the outline doesn’t strictly follow the CSS box model for an HTML element. In the provided example, observe the specific configuration where the outline-offset is defined as 8 pixels.

body {
  background: #c387eb;
  padding: 0 24px;
  margin: 0;
  height: 100vh;
  color: white;
  display: flex;
  justify-content: center;
  align-items: center;
}

.box {
  width: 350px;
  height: 200px;
  outline-style: double;
  outline-color: invert;
  outline-width: 10px;
  outline-offset: 8px;
  padding: 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

<body>
  <div class="box">
    <h1>outline-offset: 8px;</h1>
  </div>
</body>

Setting Outline Style to auto

The outline-style property in CSS allows you to set the style of an outline around an element. Outlines are drawn outside of any borders and do not take up space in the document flow.

The auto value for outline-style is not meant to specify a custom style. Instead, when outline-style is set to auto, the browser will determine the style of the outline to use based on the element’s type.

For example, buttons may receive a dotted outline while other elements receive a solid outline. Browsers have some predefined behaviors for applying outlines with auto, but they may differ slightly between browsers.

Conclusively, the auto value allows browsers to handle determining the most appropriate outline style instead of having to explicitly set the style yourself. This allows for some built-in accessibility capabilities and while the styles may vary across browsers, it prevents having to reset styles for all element types.

Setting the Outline Width

The outline-width property in CSS specifies the thickness of the outline to render around an element. We can set the width using standard length values or keyword values.

For example:

.box {
  /* Set outline width in px */
  outline-width: 5px;
}

.box-2 {
  /* Set outline width using keyword */
  outline-width: medium;
}

Valid values for outline-width include:

  • Length values: Sets a fixed width using units like px, em, rem, etc.

  • Keywords: thin, medium, thick-set a preset width.

Percentage or negative values are invalid for outline-width. The value must be a positive length or keyword.

Using different outline-widths allows for varying the visual prominence of the outline based on the design needs. Keywords like medium are often good starting points before fine-tuning from there.

CSS Outline Style

The outline-style property specifies outline-style. It is available in any one of the following values: The following examples show the different outline-styles:

Understanding the Different Outline Styles

The style property defines the outline style for elements. It may include one of two values if the property is outline-like. We will examine this example which explains the differences between outline-style and adverb type. None is displayed without an outline. The values inset, outset grooves and ridges provide similar 3D effects depending largely on the outline color values. This can be achieved primarily using two colors slightly lighter and darker than the outline color to form shadows.

CSS Outline Color

The outline-style property in CSS allows you to set the style of the outline that is rendered around an element. There are a variety of available values for outline-style:

- dotted    - Creates a dotted outline
- dashed    - Creates a dashed outline
- solid     - Creates a solid outline (default)
- double    - Creates a double outline
- groove    - Applies a 3D grooved effect
- ridge     - Applies a 3D ridged effect
- inset     - Creates an inset looking effect
- outset    - Creates an outset-looking effect

For example, here is how you could set a dashed outline style:

.element {
  outline-style: dashed;
}

And here is an element with a double outline style:

.element {
  outline-style: double;
}

The different outline styles allow for the creation of various effects to best suit the desired design needs. Solid is the default style, but dotted and dashed outlines can work well to subtly call attention to elements. Double outlines can also effectively highlight items on the page.

Difference Between Outline and Border in CSS

  • Borders are used for design, while outlines are used for accessibility.

  • An outline resembles the border, but differs in many aspects from a border: Note that if you put an outline over an element it takes more area than the outline on the webpage that you have on the element. They overlap edges (transparent areas outside borders) and nearby objects.

  • Borders are drawn on the edge of an element, while outlines are drawn outside the element’s border.

  • As demonstrated, the outline circumscribes the element, extending beyond its boundaries and potentially overlapping neighboring elements. Unlike borders which remain confined within an element’s allotted space, outlines disregard other page components, obscuring anything in their path.

  • Borders are part of the element’s dimensions, while outlines are not.

  • This core behavioral difference between outlines and borders relates to their relationship with the box model. Outlines do not factor into size calculations, enabling them to violate space owned by other elements. One must comprehend this key distinction to determine if outlines or borders better serve the intended style and layout goals. Understanding how outlines function compared to borders assists developers in leveraging the appropriate tool to achieve their desired visual effects.

  • The CSS border properties allow you to specify the style and color of an element’s border. An outline is a line that is drawn around elements (outside the borders) to make the element “stand out”. The outline shorthand property sets all the outline properties in one declaration.

  • Browsers automatically render outlines around form elements like buttons, text areas, and inputs.

Do you prefer to learn through videos? Check out this 8-min video on everything you need to learn about CSS outline:

Frequently Asked Questions

What is an outline in CSS?

An outline in CSS is a line that is drawn around an element, outside of its borders. Outlines allow elements to stand out visually without affecting the layout.

What CSS properties control outlines?

The main CSS properties for outlines include:

  • outline-style – Controls style of line (solid, dotted, etc.)

  • outline-width – Sets the width of the outline

  • outline-color – Sets the color of the outline

  • outline-offset – Creates space between the border and outline

How is an outline different from a border?

Borders take up space and alter an element’s dimensions. Outlines do not affect layout – they are drawn over the top of content without changing the document flow.

Can I put an outline around the text?

Yes, outlines can be added to text by applying them to inline or block text elements. For WebKit browsers, the text-stroke property can also outline text.

Why use outlines in CSS?

Outlines visually set apart elements without shifting content. This is useful for highlighting interactive components or improving accessibility. Outlines create noticeable separators without distorting the layout.

How do I customize an outline’s style?

Set properties like outline-style, outline-color, outline-width, and outline-offset to change an outline’s appearance. border-radius can also adjust the corner shape. This gives full control over outlines.

Can I outline text in CSS?

An HTML outline property is drawn around a component that does not change the layout. It includes outline shorthands and outline width, outline-styles, outline-color, and outline-offset.

Why do we need to put a CSS outline on your webpage?

The CSS outline property draws borders on a component without affecting the layout, making it the perfect tool to highlight. It includes outline shorthand, outline width, outline style, outline colors, and outline offset.

Should I use an outline or a border?

Borders represent a line in an element containing the content of the item, and cannot be manipulated beyond their limits in any way. Outlines, however, surround an entire element so the elements are not bound and overtake the boundary for a more recognizable image.

What is CSS border and CSS outline?

When creating border websites, web developers use the border property, which allows them to customize a border differently, such as width, color, or style. It has a similar outline on each side. Borders can change dimensions or width if an object overlaps with the elements in its components.

Wrapping Up

In this article, you learned the basics of using CSS outlines to create borders around elements that do not affect layout. You now understand that the outline properties allow you to control the style, width, and color of outlines without impacting other elements.

Specifically, you learned how outline-style lets you make dotted, dashed, double, and other types of outline effects. outline-width modifies thickness without changing an element’s dimensions. And outline-color sets the hue – using values like hex codes and color names.

Additionally, you grasped key differences between outlines and borders. Most importantly, you now know that outlines do not take up space like borders do. They overlay other elements without causing positioning shifts.

You also saw examples demonstrating these concepts visually through annotated code blocks and rendered illustrations. By the end, you gained the ability to leverage outlines for highlighting, accessibility, decorative effects, and more without disrupting document flow.

Your Next Steps

The key is that CSS outlines provide decorative standalone lines around elements. By controlling their style properties, you can customize these separators creatively according to your specific needs. You now have the essential knowledge to employ outlines effectively in your CSS designs.

Check out Purecode.ai for all you need to quickly create responsive re-usable CSS components for your web projects.

Emmanuel Uchenna

Emmanuel Uchenna

Emmanuel is an experienced and enthusiastic software developer and technical writer with 4+ proven years of professional experience. He focuses on full-stack web development. He is fluent in React, TypeScript, VueJS, and NodeJS and familiar with industry-standard technologies such as version control, headless CMS, and JAMstack. He is passionate about knowledge sharing.