CSS Logical Properties and Values

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Now that cross-browser help is at a tipping level, it’s a superb time to check out logical properties and values. In the event you’re creating a web site in a number of languages, logical properties and values are extremely helpful. Even when you’re not, there are nonetheless some handy new shorthands it’s value understanding about.

For instance, I’ve misplaced rely of the quantity of instances I’ve written this to heart one thing:

.factor {
margin-left: auto;
margin-right: auto;

We may make it a one-liner with one thing like margin: 0 auto; however then the highest and backside margins get thrown into the combo. As an alternative, we will choose simply the left and proper margin with the margin-inline logical property.

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Begin considering of issues as “inline” or “block”

That final demo is fairly neat, proper? The margin-inline property units each margin-left and margin-right. Equally, the margin-block property units each margin-top and margin-bottom. And we’re not solely speaking margins. Logical properties has related shorthands to set border and padding. So when you’ve got a visible design that requires borders solely on the perimeters, you’ll be able to simply use border-inline as a substitute of fussing with every bodily course by itself.

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Moderately than considering in bodily phrases, like left and proper, we will consider an “inline” course and a “block” course.

So, as we transfer forward, we now know that we’re coping with inline and block instructions as a substitute of bodily instructions. Inline handles the left and proper instructions, whereas block manages prime and backside.

That’s, till issues get swapped round when the writing-mode adjustments.

Take note of course and writing mode

What we’ve seen to this point are examples of CSS logical properties. These are variations of CSS properties had been used to love margin and padding, however written in a brand new manner that forgoes bodily instructions (i.e. left, proper, prime, and backside).

CSS was developed with the English language in thoughts and English is written and skim from left-to-right. That’s not the case for all languages although. Arabic, for instance, is learn from right-to-left. That’s why HTML has a dir attribute.

<html dir=”rtl”>

CSS has an equal property (though it’s beneficial to make use of the HTML attribute simply in case the CSS fails to load):

.foreign-language { course: rtl; }

Credit score: Ahmad Shadeed

Chinese language, Japanese, Korean and Mongolian may be written both horizontally from left-to-right, or vertically from prime to backside. The vast majority of web sites in these languages are written horizontally, the identical as with English.

Comparatively, vertical writing is extra widespread on Japanese web sites. Some websites use a combination of each vertical and horizontal textual content.


When written vertically, Chinese language, Japanese and Korean are written with the top-right as a place to begin, whereas Mongolian reads from left to proper. That is precisely why we now have the writing-mode property in CSS, which incorporates the next values:

horizontal-tb: That is the default worth, setting the the course left-to-right for languages like English or French, and right-to-left languages like Arabic. The tb stands for “top-to-bottom.”vertical-rl: This adjustments the course to right-to-left in a vertical orientation for languages like Chinese language, Japanese and Korean.vertical-lr: That is used for vertical left-to-right languages, like Mongolian.

CSS logical properties provide a strategy to write CSS that’s contextual. When utilizing logical properties, spacing and format are depending on each the writing-mode and course (whether or not set by both CSS or HTML). It subsequently turns into attainable to reuse CSS kinds throughout completely different languages. BBC Information, for instance, rebuild their web site in over a dozen languages. That’s a greater expertise than leaving customers to depend on autotranslate. It additionally means they’ll higher cater particular content material to completely different components of the world. The visible styling although, stays a lot the identical throughout areas.


Let’s have a look at the instance under to see the shortcomings of bodily properties. Utilizing the bodily margin-left property (proven in purple), the whole lot appears good in English. In the event you had been to reuse the CSS however change the writing mode to rtl (proven on the backside) there’s no house between the textual content and the icon and there’s extra white house on the left of the textual content. We will keep away from this through the use of a logical property as a substitute.

What makes logical properties and values so helpful is that they may routinely cater to the context of the language. In a left-to-right language like English, margin-inline-start will set the left-side margin. For a right-to-left language like Arabic, Urdu, or Hebrew, it’ll set the right-hand margin — which solves the format downside within the above instance. That’s right-to-left taken care of. If in case you have vertical textual content, margin-inline-start will cater to that context to, including the margin on the prime, which is the place you’ll begin studying from in any vertical language (that’s why it’s known as margin-inline-start — simply take into consideration which course you begin studying from). The course of inline adjustments based mostly on the component’s writing-mode. When a vertical writing-mode is about, it handles the vertical course prime and backside. See how issues can get switched round?

An instance of the writing course in Mongolian. (Credit score: W3C)

An entire listing of logical properties and values

There are dozens of CSS properties which have a logical different syntax. Adrian Roselli has a helpful visualization the place you’ll be able to toggle between the bodily CSS properties that we’re all used to and their logical property equivalents. It’s a pleasant strategy to visualize logical properties and the bodily properties they map to when the course is ltr and the writing-mode is horizontal-tb.

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Let’s break all of these down even additional and map each bodily CSS property to its logical companion, side-by-side. The tables proven all through this text present conventional bodily CSS within the left column and their logical equivalents (utilizing a left-to-right horizontal mapping) in the precise column. Keep in mind although, the entire level of logical properties is that they alter based mostly on context!


In a horizontal writing mode, inline-size units the width of a component, whereas block-size units the peak. In a vertical writing mode, the other is true: inline-size units the peak and block-size units the width.

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Bodily propertyLogical propertywidthinline-sizemax-widthmax-inline-sizemin-widthmin-inline-sizeheightblock-sizemax-heightmax-block-sizemin-heightmin-block-size

Logical properties for sizing have good cross-browser help.


Every little thing right here has strong cross-browser help amongst fashionable browsers.

Bodily propertyLogical propertyborder-topborder-block-startborder-bottomborder-block-endborder-leftborder-inline-startborder-rightborder-inline-end

Right here’s an instance of utilizing border-inline-start proven with English, Arabic, and Chinese language.

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Right here’s an instance that units border-block-start dotted and border-block-end dashed:

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There are additionally logical properties for setting the border coloration, width, and elegance individually:

Bodily propertyLogical propertyborder-top-colorborder-block-start-colorborder-top-widthborder-block-start-widthborder-top-styleborder-block-start-style

So, once more, it’s about considering when it comes to “inline” and “block” as a substitute of bodily instructions, like left and prime. We even have shorthand logical properties for borders:

Bodily propertyLogical propertyborder-top and border-bottomborder-blockborder-left and border-rightborder-inline


Listed here are all the person logical margin properties:

Bodily propertyLogical propertymargin-topmargin-block-startmargin-bottommargin-block-endmargin-leftmargin-inline-startmargin-rightmargin-inline-end

These logical properties has complete fashionable cross-browser help, together with Samsung Web, and has been supported in Safari since 12.2.

And, keep in mind, we now have the shorthands as properly:

Bodily propertyLogical propertymargin-top and margin-bottommargin-blockmargin-left and margin-rightmargin-inline


Padding is tremendous much like margin. Substitute margin with padding and we’ve obtained the identical listing of properties.

Bodily propertyLogical propertypadding-toppadding-block-startpadding-bottompadding-block-endpadding-leftpadding-inline-startpadding-rightpadding-inline-endpadding-top and padding-bottompadding-blockpadding-left and padding-rightpadding-inline

Similar to margins, logical properties for padding have good cross-browser help.


Must offset a component’s place in a sure course? We will declare these logically, too.

Bodily propertyLogical propertytopinset-block-startbottominset-block-endleftinset-inline-startrightinset-inline-endtop and bottominset-blockleft and rightinset-inline

In a horizontal writing mode (both left-to-right, or right-to-left) inset-block-start is equal to setting prime, and inset-block-end is equal to setting backside. In a horizontal writing mode, with a left-to-right course, inset-inline-start is equal to left, whereas inset-inline-end is equal to proper, and vice-versa for right-to-left languages.

Conversely, for a vertical writing mode, inset-inline-start is equal to prime whereas inset-inline-end is equal to backside. If writing-mode is about to vertical-rl, inset-block-start is equal to proper and inset-block-end is equal to left. If the writing-mode is about to vertical-lr, the other is the case and so inset-block-start is equal to left.

Logical propertyWriting modeEquivalent to:inset-block-start`Horizontal LTRtopinset-block-startHorizontal RTLtopinset-block-startVertical LTRleftinset-block-startVertical RTLright

Right here’s an instance of how the identical CSS code for absolute positioning appears in every of the 4 completely different writing instructions:

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Logical properties for positioning are supported in all fashionable browsers, however solely not too long ago landed in Safari.

There’s additionally a brand new shorthand for setting all 4 offsets in a single line of code. Right here’s an instance utilizing inset as a shorthand for setting prime, backside, left, and proper in a single fell swoop to create a full-page overlay:

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I’ve heard inset incorrectly known as a logical property. However, a fast look in DevTools exhibits that it’s truly a shorthand for bodily values, not logical properties:

What it’s truly doing is defining bodily offsets (i.e. left, proper, prime and backside) fairly than logical ones (i.e. inline, block, begin and finish). Clearly if you wish to set the identical worth for all 4 sides, as within the instance above, it doesn’t matter.

inset: 10px 20px 5px 8px; /* shorthand for bodily properties not logical properties */

Textual content alignment

Logical values for textual content alignment get pleasure from nice browser help and have for a few years. When working in English, text-align: begin is identical as text-align: left, whereas text-align: finish is identical as text-align-right. In the event you set the dir attribute to rtl, they change and text-align: begin aligns textual content to the precise.

Bodily valueWriting modeEquivalent to:startLTRleftstartRTLrightendLTRrightendRTLleft

Border radius

To this point the whole lot we’ve checked out has first rate browser help. Nevertheless, there are another logical properties the place help remains to be a piece in progress, and border radius is one among them. In different phrases, we will set a distinct border-radius worth for various corners of a component utilizing logical properties, however browser help isn’t nice.

Bodily propertyLogical propertyborder-top-left-radiusborder-start-start-radiusborder-top-right-radiusborder-start-end-radiusborder-bottom-left-radiusborder-end-start-radiusborder-bottom-right-radiusborder-end-end-radius

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It’s value noting that the spec doesn’t embody shorthand properties, like border-start-radius and border-end-radius. However, like I stated, we’re nonetheless in early days right here, in order that is perhaps an area to observe.


Move-relative values for logical floats have horrible browser help on the time I’m scripting this. Solely Firefox helps inline-start and inline-end as float values.

Bodily valueLogical valuefloat: leftfloat: inline-startfloat: rightfloat: inline-endclear: leftclear: inline-startclear: rightclear: inline-end

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Different logical properties

There are proposed logical properties for overflow and resize, however they presently have horrendous browser help.

PhysicalLogicalresize: verticalresize: blockresize: horizontalresize: inlineoverflow-yoverflow-blockoverflow-xoverflow-inline

Digging deeper

We explored what it means for a property to be thought-about “logical” after which mapped out all the new logical properties and values to their bodily counterparts. That’s nice! However if you wish to go even deeper into CSS Logical Properties and Values, there are a variety of assets value testing.

“RTL Styling 101” (Ahmad Shadeed): An incredible useful resource when you’re coping with Arabic or different right-to-left languages. Ahmad covers the whole lot, from logical properties to issues when working with particular format strategies, like flexbox and grid.text-combine-upright (CSS-Methods): In the event you’re coping with vertical textual content, do you know that this property can rotate textual content and squeeze a number of characters into the house of a single character? It’s a pleasant contact of refinement in particular conditions the place some characters must go collectively however nonetheless circulate with a vertical writing mode.

If you wish to view some good real-world examples of vertical typography from throughout the online, check out the Net Awards for Horizontal and Vertical Writings. There’s numerous nice stuff in there.

Wrapping up

Do it’s essential rush and swap all the bodily properties out of your codebase? Nope. But it surely additionally doesn’t harm to start out utilizing logical properties and values in your work. As we’ve seen, browser help is just about there. And even when you’re engaged on a website that’s simply in English, there’s no motive to not use them.

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