The inset-block-start CSS property defines the logical block start offset of an element, which maps to a physical inset depending on the element's writing mode, directionality, and text orientation. It corresponds to the top, right, bottom, or left property depending on the values defined for writing-mode, direction, and text-orientation.

/* <length> values */ inset-block-start: 3px; inset-block-start: 2.4em;  /* <percentage>s of the width or height of the containing block */ 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: unset; 

inset-block-start

The inset-block-start CSS property defines the logical block start offset of an element, which maps to a physical inset depending on the element's writing mode, directionality, and text orientation. It corresponds to the top, right, bottom, or left property depending on the values defined for writing-mode, direction, and text-orientation.

/* <length> values */ inset-block-start: 3px; inset-block-start: 2.4em;  /* <percentage>s of the width or height of the containing block */ 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: unset; 

Syntax

Values

The inset-block-start property takes the same values as the left property.

Formal definition

Initial value	auto
Applies to	positioned elements
Inherited	no
Percentages	logical-height of containing block
Computed value	same as box offsets: top, right, bottom, left properties except that directions are logical
Animation type	a length, percentage or calc();

Formal syntax

<'top'>

Examples

Setting block start offset

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; } 

Specifications

Specification
CSS Logical Properties and Values Level 1 # position-properties

See also

The properties which defines other insets: inset-block-end, inset-inline-start, and inset-inline-end The mapped physical properties: top, right, bottom, and left writing-mode, direction, text-orientation

Last modified: Aug 12, 2021, by MDN contributors

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