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CSS Reference

CSS Reference CSS Browser Support CSS Selectors CSS Functions CSS Reference Aural CSS Web Safe Fonts CSS Fallback Fonts CSS Animatable CSS Units CSS PX-EM Converter CSS Colors CSS Color Values CSS Default Values CSS Entities

CSS Properties

accent-color align-content align-items align-self all animation animation-delay animation-direction animation-duration animation-fill-mode animation-iteration-count animation-name animation-play-state animation-timing-function aspect-ratio backdrop-filter backface-visibility background background-attachment background-blend-mode background-clip background-color background-image background-origin background-position background-position-x background-position-y background-repeat background-size block-size border border-block border-block-color border-block-end-color border-block-end-style border-block-end-width border-block-start-color border-block-start-style border-block-start-width border-block-style border-block-width border-bottom border-bottom-color border-bottom-left-radius border-bottom-right-radius border-bottom-style border-bottom-width border-collapse border-color border-end-end-radius border-end-start-radius border-image border-image-outset border-image-repeat border-image-slice border-image-source border-image-width border-inline border-inline-color border-inline-end-color border-inline-end-style border-inline-end-width border-inline-start-color border-inline-start-style border-inline-start-width border-inline-style border-inline-width border-left border-left-color border-left-style border-left-width border-radius border-right border-right-color border-right-style border-right-width border-spacing border-start-end-radius border-start-start-radius border-style border-top border-top-color border-top-left-radius border-top-right-radius border-top-style border-top-width border-width bottom box-decoration-break box-reflect box-shadow box-sizing break-after break-before break-inside caption-side caret-color @charset clear clip clip-path color column-count column-fill column-gap column-rule column-rule-color column-rule-style column-rule-width column-span column-width columns content counter-increment counter-reset cursor direction display empty-cells filter flex flex-basis flex-direction flex-flow flex-grow flex-shrink flex-wrap float font @font-face font-family font-feature-settings font-kerning font-size font-size-adjust font-stretch font-style font-variant font-variant-caps font-weight gap grid grid-area grid-auto-columns grid-auto-flow grid-auto-rows grid-column grid-column-end grid-column-gap grid-column-start grid-gap grid-row grid-row-end grid-row-gap grid-row-start grid-template grid-template-areas grid-template-columns grid-template-rows hanging-punctuation height hyphens image-rendering @import inline-size inset inset-block inset-block-end inset-block-start inset-inline inset-inline-end inset-inline-start isolation justify-content justify-items justify-self @keyframes left letter-spacing line-height list-style list-style-image list-style-position list-style-type margin margin-block margin-block-end margin-block-start margin-bottom margin-inline margin-inline-end margin-inline-start margin-left margin-right margin-top mask-image mask-mode mask-origin mask-position mask-repeat mask-size max-block-size max-height max-inline-size max-width @media min-block-size min-inline-size min-height min-width mix-blend-mode object-fit object-position offset offset-anchor offset-distance offset-path offset-rotate opacity order orphans outline outline-color outline-offset outline-style outline-width overflow overflow-anchor overflow-wrap overflow-x overflow-y overscroll-behavior overscroll-behavior-block overscroll-behavior-inline overscroll-behavior-x overscroll-behavior-y padding padding-block padding-block-end padding-block-start padding-bottom padding-inline padding-inline-end padding-inline-start padding-left padding-right padding-top page-break-after page-break-before page-break-inside paint-order perspective perspective-origin place-content place-items place-self pointer-events position quotes resize right rotate row-gap scale scroll-behavior scroll-margin scroll-margin-block scroll-margin-block-end scroll-margin-block-start scroll-margin-bottom scroll-margin-inline scroll-margin-inline-end scroll-margin-inline-start scroll-margin-left scroll-margin-right scroll-margin-top scroll-padding scroll-padding-block scroll-padding-block-end scroll-padding-block-start scroll-padding-bottom scroll-padding-inline scroll-padding-inline-end scroll-padding-inline-start scroll-padding-left scroll-padding-right scroll-padding-top scroll-snap-align scroll-snap-stop scroll-snap-type tab-size table-layout text-align text-align-last text-decoration text-decoration-color text-decoration-line text-decoration-style text-decoration-thickness text-indent text-justify text-orientation text-overflow text-shadow text-transform top transform transform-origin transform-style transition transition-delay transition-duration transition-property transition-timing-function translate unicode-bidi user-select vertical-align visibility white-space widows width word-break word-spacing word-wrap writing-mode z-index



CSS Units


CSS Units

CSS has several different units for expressing a length.

Many CSS properties take "length" values, such as width, margin, padding, font-size, etc.

Length is a number followed by a length unit, such as 10px, 2em, etc.

Example

Set different length values, using px (pixels):

h1 {
  font-size: 60px;
}

p {
  font-size: 25px;
  line-height: 50px;
}

Try it Yourself »

Note: A whitespace cannot appear between the number and the unit. However, if the value is 0, the unit can be omitted.

For some CSS properties, negative lengths are allowed.

There are two types of length units: absolute and relative.


Absolute Lengths

The absolute length units are fixed and a length expressed in any of these will appear as exactly that size.

Absolute length units are not recommended for use on screen, because screen sizes vary so much. However, they can be used if the output medium is known, such as for print layout.

Unit Description
cm centimeters Try it
mm millimeters Try it
in inches (1in = 96px = 2.54cm) Try it
px * pixels (1px = 1/96th of 1in) Try it
pt points (1pt = 1/72 of 1in) Try it
pc picas (1pc = 12 pt) Try it

* Pixels (px) are relative to the viewing device. For low-dpi devices, 1px is one device pixel (dot) of the display. For printers and high resolution screens 1px implies multiple device pixels.


Relative Lengths

Relative length units specify a length relative to another length property. Relative length units scale better between different rendering medium.

Unit Description
em Relative to the font-size of the element (2em means 2 times the size of the current font) Try it
ex Relative to the x-height of the current font (rarely used) Try it
ch Relative to the width of the "0" (zero) Try it
rem Relative to font-size of the root element Try it
vw Relative to 1% of the width of the viewport* Try it
vh Relative to 1% of the height of the viewport* Try it
vmin Relative to 1% of viewport's* smaller dimension Try it
vmax Relative to 1% of viewport's* larger dimension Try it
% Relative to the parent element Try it

Tip: The em and rem units are practical in creating perfectly scalable layout!
* Viewport = the browser window size. If the viewport is 50cm wide, 1vw = 0.5cm.



Browser Support

The numbers in the table specify the first browser version that fully supports the length unit.

Length Unit
em, ex, %, px, cm, mm, in, pt, pc 1.0 3.0 1.0 1.0 3.5
ch 27.0 9.0 1.0 7.0 20.0
rem 4.0 9.0 3.6 4.1 11.6
vh, vw 20.0 9.0 19.0 6.0 20.0
vmin 20.0 12.0 19.0 6.0 20.0
vmax 26.0 16.0 19.0 7.0 20.0