CSS inset-block-start Adaptive Positioning

Introduction

The inset-block-start CSS property is a handy tool for web developers. Introduced in September 2021, it helps control the position of an element based on its writing mode, direction, and text orientation. This makes it great for creating responsive designs.

inset-block-start works similarly to top, right, bottom, or left, but it adapts to different text flows. This flexibility is crucial for supporting various languages and writing systems.

Baseline Widely Available

The inset-block-start property is widely supported across many devices and browsers. This means you can use it confidently in your projects without worrying about compatibility issues.

Definition and Usage

The inset-block-start property defines the logical block start offset of an element. This offset changes based on the writing mode and direction. For example, in a vertical writing mode, it might align an element to the top, while in a horizontal mode, it might align to the left.

Key Points:

• Logical Positioning: Positions elements based on the logical block start.
• Adaptive Design: Supports different writing systems and text orientations.
• Corresponding Physical Properties: Maps to top, right, bottom, or left depending on the writing mode.

Syntax

The syntax for inset-block-start is simple and flexible. Here’s how you can use it:

/* Length values */
inset-block-start: 3px;
inset-block-start: 2.4em;
inset-block-start: calc(50% + 10px);

/* Percentage values */
inset-block-start: 10%;

/* Keyword value */
inset-block-start: auto;

/* Global values */
inset-block-start: inherit;
inset-block-start: initial;
inset-block-start: revert;
inset-block-start: revert-layer;
inset-block-start: unset;

Values

The inset-block-start property accepts various values, including lengths, percentages, and keywords.

Length Values

Use specific units like pixels (px) or em units (em).

inset-block-start: 3px;
inset-block-start: 2.4em;

Percentage Values

Set the offset as a percentage of the containing block’s logical height.

inset-block-start: 10%;

Keyword Values

The auto keyword lets the browser determine the offset automatically.

inset-block-start: auto;

Global Values

Global values like inherit, initial, revert, revert-layer, and unset provide additional control.

inset-block-start: inherit;
inset-block-start: initial;
inset-block-start: revert;
inset-block-start: revert-layer;
inset-block-start: unset;

Formal Definition

The inset-block-start property controls the logical block start offset of an element. It’s particularly useful for positioning elements that adapt to different writing modes and directions.

Initial Value

• Initial Value: auto

Applies To

• Applies To: Positioned elements

Inherited

• Inherited: No

Percentages

• Percentages: Refers to the logical height of the containing block

Computed Value

• Computed Value: The same as box offsets (top, right, bottom, left) but with directions being logical

Animation Type

• Animation Type: A length, percentage, or calc()

Formal Syntax

inset-block-start =
  auto |
  <length-percentage>

<length-percentage> =
  <length> |
  <percentage>

Examples

Setting Block Start Offset

Here’s how to use inset-block-start to position a paragraph within a div element.

HTML

<div>
  <p class="exampleText">Example text</p>
</div>

CSS

div {
  background-color: yellow;
  width: 120px;
  height: 120px;
}

.exampleText {
  writing-mode: vertical-lr;
  position: relative;
  inset-block-start: 20px;
  background-color: #c8c800;
}

Result

The paragraph will be positioned 20 pixels from the logical block start of the div. The writing-mode: vertical-lr; sets the text to flow from top to bottom and left to right.

Specifications

The inset-block-start property is defined in the CSS Logical Properties and Values Level 1 specification. This specification outlines logical properties that adapt to different writing modes and directions.

Key Specification

• CSS Logical Properties and Values Level 1: This specification introduces logical properties and values for more intuitive and flexible layout control.

Link to Specification

• CSS Logical Properties and Values Level 1 - Position Properties

Browser Compatibility

The inset-block-start property is widely supported across many devices and browsers, making it a reliable tool for web developers.

Compatibility Table

• Firefox: Supported since version 63
• Google Chrome: Supported since version 87
• Edge: Supported since version 87
• Opera: Supported since version 73
• Safari: Supported since version 14.1

Checking Compatibility

For the latest info on browser compatibility, check out the Browser Compatibility Data (BCD) tables.

Related Properties and Concepts

To get the most out of inset-block-start, consider exploring related CSS properties:

• Related Inset Properties:

  • inset-block-end
  • inset-inline-start
  • inset-inline-end

• Mapped Physical Properties:

  • top
  • right
  • bottom
  • left

• Writing Mode and Direction Properties:

  • writing-mode
  • direction
  • text-orientation

Supported Browsers

The inset-block-start property is supported by the following browsers:

• Firefox: Version 63 and later
• Google Chrome: Version 87 and later
• Edge: Version 87 and later
• Opera: Version 73 and later
• Safari: Version 14.1 and later

With such broad support, you can confidently use inset-block-start in your projects, ensuring compatibility across different browsers and devices. This property is great for creating adaptive and responsive layouts that enhance user experience.

By exploring related properties, you can deepen your understanding and make even better use of inset-block-start in your web development. This will help you create layouts that work seamlessly across various devices and browsers.