Tillitsdone
down Scroll to discover

CSS Outline A Comprehensive Guide for Web Designers

Learn about the CSS outline property, its use cases, and available options.

Enhance your web design with accessible and visually appealing outlines.
thumbnail

Introduction

The outline CSS property is a shorthand that lets you define multiple outline properties in one go. It’s useful for adding stylish borders around elements without affecting the layout. Outlines are lines that appear outside an element’s border and do not take up space, making them ideal for accessibility features like focus indicators.

Specification

The outline property is defined by the CSS Basic User Interface Module Level 4 (CSS UI Level 4). This specification ensures consistent behavior across different browsers and platforms.

Constituent Properties

The outline property combines several individual outline properties:

  1. outline-width:
    • Sets the thickness of the outline.
    • Defaults to medium if not specified.
    • Examples: thin, medium, thick, or any CSS length value (e.g., 2px, 1em).
  2. outline-style:
    • Defines the style of the outline.
    • Defaults to none if not specified.
    • Examples: none, dotted, dashed, solid, double, groove, ridge, inset, outset.
  3. outline-color:
    • Specifies the color of the outline.
    • Defaults to currentcolor.
    • Examples: red, #ff0000, rgb(255, 0, 0), hsl(0, 100%, 50%).

These properties can be set individually or combined using the outline shorthand. Any omitted values will default to their initial settings.

Syntax

The outline property syntax:

outline: [<'outline-width'> || <'outline-style'> || <'outline-color'>] | initial | inherit | revert | revert-layer | unset;
<outline-width> = <length [0,]> | thin | medium | thick;
<outline-style> = auto | <outline-line-style>;
<outline-color> = auto | <color> | <image-1D>;
<image-1D> = <stripes()>;
<stripes()> = stripes( <color-stripe># );
<color-stripe> = <color> && ( <length-percentage> | <flex> )?;
<length-percentage> = <length> | <percentage>;

Values

The outline property accepts various values to customize the appearance:

  1. <'outline-width'>:
    • Sets the thickness of the outline.
    • Default Value: medium if absent.
    • Example Values: thin, medium, thick, or any valid CSS length value (e.g., 2px, 1em).
  2. <'outline-style'>:
    • Defines the style of the outline.
    • Default Value: none if absent.
    • Example Values: none, dotted, dashed, solid, double, groove, ridge, inset, outset.
  3. <'outline-color'>:
    • Specifies the color of the outline.
    • Default Value: currentcolor.
    • Example Values: Any valid CSS color value, such as red, #ff0000, rgb(255, 0, 0), or hsl(0, 100%, 50%).

Examples

Setting the style only:

outline: solid;

Setting the style and color:

outline: dashed #f66;

Setting the width and style:

outline: thick inset;

Setting the width, style, and color:

outline: 3px solid green;

Using global values:

outline: inherit;
outline: initial;
outline: revert;
outline: revert-layer;
outline: unset;

Key Points

  • Order of Values: The order does not matter. For example, outline: 3px solid green; is the same as outline: green solid 3px;.
  • Default Values: Omitted properties default to initial values.
  • Global Values: Accepts global values like initial, inherit, revert, revert-layer, and unset.

Description

An outline is a special type of border that appears outside an element’s actual border and does not take up space in the layout. This makes outlines useful for adding visual emphasis without affecting the document’s structure. Outlines are often used for focus indicators, essential for accessibility.

Accessibility

The outline property is crucial for web accessibility by providing visual focus indicators for interactive elements like links, buttons, and form fields. These indicators are essential for users who navigate using keyboards or assistive technologies.

Best Practices for Accessibility

  1. Maintain Visibility: Ensure the outline is visible and contrasts well with the background.
  2. Avoid Removing Outlines: If removing the default outline, provide an alternative focus indicator.
  3. Use Additional Styles: Enhance visibility with properties like border, background-color, or box-shadow.

Example of Accessible Focus Style

<a href="#">This link has a custom focus style.</a>
a:focus {
outline: 4px dotted #e73;
outline-offset: 4px;
background: #ffa;
}

Formal Definition

The outline property is a shorthand that combines several individual properties:

Initial Value:

  • outline-width: medium
  • outline-style: none
  • outline-color: currentcolor

Applies To: All elements.

Inherited: No.

Computed Value:

  • outline-width: Computed value as specified for the width.
  • outline-style: Computed value as specified for the style.
  • outline-color: Computed value as specified for the color.

Animation Types

  • outline-width: Can be animated as a length.
  • outline-style: Can be animated by computed value type.
  • outline-color: Can be animated as a color.

Browser Compatibility

The outline property is widely supported across major browsers.

Desktop Browsers

  • Google Chrome: Full support since version 1.0.
  • Mozilla Firefox: Full support since version 1.5.
  • Microsoft Edge: Full support since version 12.
  • Internet Explorer: Partial support starting from version 8.0.
  • Opera: Full support since version 7.0.
  • Safari: Full support since version 1.2.

Mobile Browsers

  • Chrome for Android: Full support since version 18.
  • Firefox for Android: Full support since version 4.0.
  • Safari on iOS: Full support since iOS 3.2.
  • Opera Mobile: Full support since version 10.
  • Samsung Internet: Full support since version 1.0.

Resources for Browser Compatibility

  • MDN Web Docs: [CSS outline Property]WebsiteUrl
  • Can I Use: [Outline Property]WebsiteUrl

Conclusion

The outline property in CSS is a powerful tool for creating visually appealing and accessible designs. Its wide browser support makes it reliable for modern web development. By understanding its capabilities, you can enhance the user experience while ensuring consistency across different devices and platforms.

icons/logo-tid.svg Latest Blogs
Discover our top articles, selected to support the growth of your business.
https://imgproxy-landing-page.tillitsdone.com/sig/rs:fit:1200:630/plain/https%3A%2F%2Fcms-r2.tillitsdone.com%2Fwp-content-prod%2Fuploads%2F2025%2F10%2FTill-its-done_SEO_R43_Sep_1440x697.jpg@webp สร้างเว็บไซต์ 1 เว็บ ต้องใช้งบเท่าไหร่? เจาะลึกทุกองค์ประกอบ website development cost อยากสร้างเว็บไซต์แต่ไม่มั่นใจในเรื่องของงบประมาณ อ่านสรุปเจาะลึกตั้งแต่ดีไซน์, ฟังก์ชัน และการดูแล พร้อมตัวอย่างงบจริงจาก Till it&#8217;s done ที่แผนชัด งบไม่บานปลายแน่นอน https://imgproxy-landing-page.tillitsdone.com/sig/rs:fit:1200:630/plain/https%3A%2F%2Fcms-r2.tillitsdone.com%2Fwp-content-prod%2Fuploads%2F2025%2F10%2FTill-its-done_SEO_R42_Sep_1440x697.jpg@webp Next.js สอน 14 ขั้นตอนเบื้องต้น: สร้างโปรเจกต์แรกใน 30 นาที เริ่มต้นกับ Next.js ใน 14 ขั้นตอนเพียงแค่ 30 นาที พร้อม SSR/SSG และ API Routes ด้วยตัวอย่างโค้ดง่าย ๆ อ่านต่อเพื่อสร้างโปรเจ็กต์แรกได้ทันทีที่นี่ https://imgproxy-landing-page.tillitsdone.com/sig/rs:fit:1200:630/plain/https%3A%2F%2Fcms-r2.tillitsdone.com%2Fwp-content-prod%2Fuploads%2F2025%2F10%2FTill-its-done_SEO_R41_Sep_1440x697.jpg@webp วิธีสมัคร Apple Developer Account เพื่อนำแอปขึ้น App Store ทีละขั้นตอน อยากปล่อยแอปบน App Store ระดับโลก มาอ่านคู่มือสมัคร Apple Developer Account พร้อมเคล็ดลับ TestFlight และวิธีอัปโหลดที่ง่ายในบทความเดียวนี้ได้เลย https://imgproxy-landing-page.tillitsdone.com/sig/rs:fit:1200:630/plain/https%3A%2F%2Fcms-r2.tillitsdone.com%2Fwp-content-prod%2Fuploads%2F2025%2F10%2FTill-its-done_SEO_R38_Sep_1440x697.jpg@webp TypeScript Interface คืออะไร? อธิบายพร้อมวิธีใช้และข้อแตกต่างจาก Type เรียนรู้วิธีใช้ TypeScript Interface เพื่อสร้างโครงสร้างข้อมูลที่ปลอดภัยและเข้าใจง่าย พร้อมเปรียบเทียบข้อดีข้อแตกต่างกับ Type ที่คุณต้องรู้ ถูกรวมเอาไว้ในบทความนี้แล้ว https://imgproxy-landing-page.tillitsdone.com/sig/rs:fit:1200:630/plain/https%3A%2F%2Fcms-r2.tillitsdone.com%2Fwp-content-prod%2Fuploads%2F2025%2F09%2FTill-its-done_SEO_R36_Sep_1440x697.jpg@webp Material-UI (MUI) คืออะไร อยากสร้าง UI สวยงามและเป็นมืออาชีพในเวลาอันรวดเร็วใช่ไหม มาทำความรู้จักกับ Material-UI (MUI) ที่ช่วยให้คุณพัฒนาแอปพลิเคชันบน React ได้ง่ายและดูดีในทุกอุปกรณ์ https://imgproxy-landing-page.tillitsdone.com/sig/rs:fit:1200:630/plain/https%3A%2F%2Fcms-r2.tillitsdone.com%2Fwp-content-prod%2Fuploads%2F2025%2F09%2FTill-its-done_SEO_R27_Sep_1440x697.jpg@webp เปรียบเทียบ 3 วิธีติดตั้ง install node js บน Ubuntu: NVM vs NodeSource vs Official Repo แบบไหนดีที่สุด? เรียนรู้วิธีติดตั้ง Node.js บน Ubuntu ด้วย NVM, NodeSource หรือ Official Repo เลือกวิธีที่เหมาะกับความต้องการของคุณ พร้อมเปรียบเทียบ เพื่อการพัฒนาที่มีประสิทธิภาพ!
icons/logo-tid.svg

Talk with CEO

Ready to bring your web/app to life or boost your team with expert Thai developers?
Contact us today to discuss your needs, and let’s create tailored solutions to achieve your goals. We’re here to help at every step!
🖐️ Contact us
down Explore our best articles, cover a wide variety of technologies
Our knowledge base
196 Articles
Explore right
icons/logo-react.svg ReactJs
Popular JavaScript library for building user interfaces with a component-based architecture.
160 Articles
Explore right
icons/flutter.svg Flutter
UI toolkit for building natively compiled applications for mobile, web, and desktop from a single codebase.
144 Articles
Explore right
icons/logo-nodejs.svg Nodejs
JavaScript runtime for building scalable, high-performance server-side applications.
58 Articles
Explore right
icons/next-js.svg Nextjs
React framework enabling server-side rendering and static site generation for optimized performance.
38 Articles
Explore right
icons/tailwind.svg TailwindCSS
Utility-first CSS framework for rapid UI development.
36 Articles
Explore right
icons/code-outline.svg Typescript
Superset of JavaScript adding static types for improved code quality and maintainability.
126 Articles
Explore right
icons/code-outline.svg Golang
Programming language known for its simplicity, concurrency model, and performance.
67 Articles
Explore right
icons/code-outline.svg AstroJs
Astro is an all-in-one web framework. It includes everything you need to create a website, built-in.
38 Articles
Explore right
icons/code-outline.svg Jest
Versatile testing framework for JavaScript applications supporting various test types.
16 Articles
Explore right
icons/code-outline.svg Website development th
11 Articles
Explore right
icons/code-outline.svg Mobile application th
5 Articles
Explore right
icons/code-outline.svg Reactjs th
4 Articles
Explore right
icons/code-outline.svg Nextjs th
3 Articles
Explore right
icons/code-outline.svg Flutter th
1 Articles
Explore right
icons/code-outline.svg Software house th
1 Articles
Explore right
icons/code-outline.svg Nodejs th
1 Articles
Explore right
icons/code-outline.svg Typescript th
337 Articles
Explore right
icons/css-4.svg CSS
CSS3 is the latest version of Cascading Style Sheets, offering advanced styling features like animations, transitions, shadows, gradients, and responsive design.
Let's keep in Touch
Thank you for your interest in Tillitsdone! Whether you have a question about our services, want to discuss a potential project, or simply want to say hello, we're here and ready to assist you.
We'll be right here with you every step of the way.
Contact Information
rick@tillitsdone.com+66824564755
Find All the Ways to Get in Touch with Tillitsdone - We're Just a Click, Call, or Message Away. We'll Be Right Here, Ready to Respond and Start a Conversation About Your Needs.
Address
9 Phahonyothin Rd, Khlong Nueng, Khlong Luang District, Pathum Thani, Bangkok Thailand
Visit Tillitsdone at Our Physical Location - We'd Love to Welcome You to Our Creative Space. We'll Be Right Here, Ready to Show You Around and Discuss Your Ideas in Person.
Social media
FacebookInstagramLinkedIn
Connect with Tillitsdone on Various Social Platforms - Stay Updated and Engage with Our Latest Projects and Insights. We'll Be Right Here, Sharing Our Journey and Ready to Interact with You.
We anticipate your communication and look forward to discussing how we can contribute to your business's success.
We'll be here, prepared to commence this promising collaboration.
Frequently Asked Questions
Explore frequently asked questions about our products and services.
Whether you're curious about features, warranties, or shopping policies, we provide comprehensive answers to assist you.