The min-width CSS descriptor specifies the minimum width of the viewport of a document defined via @viewport.

By default, min-width is set as close as possible to the initial viewport considering the minimum width constraint.

Related at-rule @viewport
Initial value auto
Percentages refer to the width of the initial viewport
Media visual, continuous
Computed value if specified as a length, the corresponding absolute length; if specified as a percentage, the specified value; otherwise, auto
Canonical order the unique non-ambiguous order defined by the formal grammar


/* Keyword value */
min-width: auto;

/* <length> values */
min-width: 320px;
min-width: 40em;
min-width: 5cm;

/* <percentage> value */
min-width: 25%;


The used value is calculated from the other CSS descriptors' values.
A non-negative absolute or relative length.
A percentage value relative to the width or height of the initial viewport at zoom factor 1.0, for horizontal and vertical lengths respectively. Must be non-negative.

Formal syntax


<viewport-length> = auto | <length-percentage>

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


Specification Status Comment
CSS Device Adaptation
The definition of '"min-width" descriptor' in that specification.
Working Draft Initial definition

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 29 (behind a flag) No support 10 -ms 11.10
Removed in 15
Reintroduced behind a flag in 16
No support
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support 4.4 29 No support 10-ms 11.10
Removed in 15
Reintroduced behind a flag in 16
No support

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