Children :before content inheritance - css

The title might be a little bit confusing but I wonder why is it impossible for a child element to inherit it's parent ::before content. for example:
HTML:
<div class="foo">
<div class="baz"></div>
</div>
CSS:
.foo::before {
content: 'bar';
}
.foo .baz::before {
content: inherit;
}
I have tried it that way, and even this way:
.foo > .baz::before {
content: inherit;
}
and this one:
.foo::before ~ .baz::before {
content: inherit;
}
...and none of the above worked... Is it possible at all? if not, which options do I have in order to achieve this?
UPDATE
I think I might found a way to do such thing:
.foo {
content: 'bar';
}
.foo > .baz,
.foo > .baz::before {
content: inherit;
}

A ::before/::after pseudo-element cannot inherit from another ::before/::after pseudo-element. A pseudo-element can only inherit from its originating element — this is the element that the pseudo-element is attached to. A pseudo-element cannot even inherit from the parent of its originating element, unless the originating element itself is also inheriting from its parent and the property involved is not content.
In your example, .foo::before can only inherit from the .foo it's attached to, and likewise for .baz::before and .baz. .baz::before cannot inherit from .foo::before, so what you're trying to do is not possible. There does not appear to be a reliable way to ensure that one pseudo-element always inherits from another pseudo-element through CSS alone without enforcing this within the markup itself.

Related

Are :before :after siblings?

The purpose of the question is to investigate the possibility of doings something like:
.element:before {
content: 'before';
color: orange;
}
.element:after {
content: 'after';
color: green;
}
.element:after:hover + .element:before {
color: red;
}
<div class='element'> </div>
Pseudo-elements cannot be targeted by sibling combinators because sibling combinators only represent element siblings, not pseudo-element siblings.
So, although the boxes generated by ::before and ::after are siblings of one another in terms of layout, for the purposes of sibling combinators they are not.
It is not possible to write a selector styling an element's ::before pseudo-element when its ::after pseudo-element is hovered. (For that matter, ::after:hover is not valid outside of Selectors 4 either, and no implementations exist.) There are hacks that make use of things like pointer-events but there is nothing that is guaranteed to work on all browsers.

Conditional css formatting

Is it possible to add conditional formatting to change class on using hover effect on a div:
.resize:hover {
height: 360px;
z-index: 1;
.font_white {
color: blue;
}
}
.font_white{
color: white;
}
Is it possible to override font_white while hovering div with resize class? These classes are independent div's.
No it's not, not using pure CSS that is.
You can use JS, but without the code of your markup, it's hard to say what the best way is.
(Of course, if the font color is to be applied inside the div you hover, it is doable using CSS only, although not the way you describe it. But I assume you want to trigger style changes across the page by hovering a div.)
There is no generic way to achieve that with CSS.
If you can write a selector that matches both the element that is a member of the resize class and the element that is a member of the font_white class (which you would do using a combinator such as descendant, child or sibling) then you can use the combinator to achieve it.
For example:
.resize:hover ~ .font_white { ... }
would work if your HTML looked something like:
<button class="resize">Hover Me</button>
<section id="first">...</section>
<section id="second" class="font_white">...</section>
<section id="third" class="font_white">...</section>
You would need to select apropriate combinators for your particular HTML.
If you rewrite your CSS, you'll see that your desired effect is possible - and achievable without redefining the style declarations of your class.
Example:
.primary-text {
color: white;
}
.resize:hover {
height: 360px;
z-index: 1;
}
.resize:hover .primary-text {
color: blue;
}

How to create css classes from existing ones? [duplicate]

Is it possible to make a CSS class that "inherits" from another CSS class (or more than one).
For example, say we had:
.something { display:inline }
.else { background:red }
What I'd like to do is something like this:
.composite
{
.something;
.else
}
where the ".composite" class would both display inline and have a red background
There are tools like LESS, which allow you to compose CSS at a higher level of abstraction similar to what you describe.
Less calls these "Mixins"
Instead of
/* CSS */
#header {
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
border-radius: 8px;
}
#footer {
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
border-radius: 8px;
}
You could say
/* LESS */
.rounded_corners {
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
border-radius: 8px;
}
#header {
.rounded_corners;
}
#footer {
.rounded_corners;
}
You can add multiple classes to a single DOM element, e.g.
<div class="firstClass secondClass thirdclass fourthclass"></div>
Rules given in later classes (or which are more specific) override. So the fourthclass in that example kind of prevails.
Inheritance is not part of the CSS standard.
Yes, but not exactly with that syntax.
.composite,
.something { display:inline }
.composite,
.else { background:red }
Keep your common attributes together and assign specific (or override) attributes again.
/* ------------------------------------------------------------------------------ */
/* Headings */
/* ------------------------------------------------------------------------------ */
h1, h2, h3, h4
{
font-family : myfind-bold;
color : #4C4C4C;
display:inline-block;
width:900px;
text-align:left;
background-image: linear-gradient(0, #F4F4F4, #FEFEFE);/* IE6 & IE7 */
}
h1
{
font-size : 300%;
padding : 45px 40px 45px 0px;
}
h2
{
font-size : 200%;
padding : 30px 25px 30px 0px;
}
The SCSS way for the given example, would be something like:
.something {
display: inline
}
.else {
background: red
}
.composite {
#extend .something;
#extend .else;
}
More info, check the sass basics
An element can take multiple classes:
.classOne { font-weight: bold; }
.classTwo { font-famiy: verdana; }
<div class="classOne classTwo">
<p>I'm bold and verdana.</p>
</div>
And that's about as close as you're going to get unfortunately. I'd love to see this feature, along with class-aliases someday.
No you can't do something like
.composite
{
.something;
.else
}
This are no "class" names in the OO sense. .something and .else are just selectors nothing more.
But you can either specify two classes on an element
<div class="something else">...</div>
or you might look into another form of inheritance
.foo {
background-color: white;
color: black;
}
.bar {
background-color: inherit;
color: inherit;
font-weight: normal;
}
<div class="foo">
<p class="bar">Hello, world</p>
</div>
Where the paragraphs backgroundcolor and color are inherited from the settings in the enclosing div which is .foo styled. You might have to check the exact W3C specification. inherit is default for most properties anyway but not for all.
I ran into this same problem and ended up using a JQuery solution to make it seem like a class can inherit other classes.
<script>
$(function(){
$(".composite").addClass("something else");
});
</script>
This will find all elements with the class "composite" and add the classes "something" and "else" to the elements. So something like <div class="composite">...</div> will end up like so: <div class="composite something else">...</div>
You can do is this
CSS
.car {
font-weight: bold;
}
.benz {
background-color: blue;
}
.toyota {
background-color: white;
}
HTML
<div class="car benz">
<p>I'm bold and blue.</p>
</div>
<div class="car toyota">
<p>I'm bold and white.</p>
</div>
Don't forget:
div.something.else {
// will only style a div with both, not just one or the other
}
You can use the converse approach to achieve the same result - start from the composite and then remove styling using the unset keyword. For example, if you start with the following sample composition:
.composite {
color: red;
margin-left: 50px;
background-color: green
}
you can then increase selector specificity to selectively remove styles using unset:
.composite.no-color {
color: unset
}
.composite.no-margin-left {
margin-left: unset
}
.composite.no-background-color {
background-color: unset
}
Here is a JSFiddle demonstrating this approach.
One benefit of this approach is that because the specificity of the compound selectors is higher than the composite itself, you do not need all of the combinations of classes to achieve the desired results for multiple combinations:
/* Multi-unset compound selector combinations, such as the one that follows, ARE NOT NECESSARY because of the higher specificity of each individual compound selectors listed above. This keeps things simple. */
.composite.no-background-color.no-color.no-margin-left {
background-color: unset;
color: unset;
margin-left: unset
}
Furthermore, at 96% support for the unset keyword, browser coverage is excellent.
Perfect timing: I went from this question to my email, to find an article about Less, a Ruby library that among other things does this:
Since super looks just like footer, but with a different font, I'll use Less's class inclusion technique (they call it a mixin) to tell it to include these declarations too:
#super {
#footer;
font-family: cursive;
}
In Css file:
p.Title
{
font-family: Arial;
font-size: 16px;
}
p.SubTitle p.Title
{
font-size: 12px;
}
I realize this question is now very old but, here goes nothin!
If the intent is to add a single class that implies the properties of multiple classes, as a native solution, I would recommend using JavaScript/jQuery (jQuery is really not necessary but certainly useful)
If you have, for instance .umbrellaClass that "inherits" from .baseClass1 and .baseClass2 you could have some JavaScript that fires on ready.
$(".umbrellaClass").addClass("baseClass1");
$(".umbrellaClass").addClass("baseClass2");
Now all elements of .umbrellaClass will have all the properties of both .baseClasss. Note that, like OOP inheritance, .umbrellaClass may or may not have its own properties.
The only caveat here is to consider whether there are elements being dynamically created that won't exist when this code fires, but there are simple ways around that as well.
Sucks css doesn't have native inheritance, though.
Unfortunately, CSS does not provide 'inheritance' in the way that programming languages like C++, C# or Java do. You can't declare a CSS class an then extend it with another CSS class.
However, you can apply more than a single class to an tag in your markup ... in which case there is a sophisticated set of rules that determine which actual styles will get applied by the browser.
<span class="styleA styleB"> ... </span>
CSS will look for all the styles that can be applied based on what your markup, and combine the CSS styles from those multiple rules together.
Typically, the styles are merged, but when conflicts arise, the later declared style will generally win (unless the !important attribute is specified on one of the styles, in which case that wins). Also, styles applied directly to an HTML element take precedence over CSS class styles.
Don't think of css classes as object oriented classes, think of them as merely a tool among other selectors to specify which attribute classes an html element is styled by. Think of everything between the braces as the attribute class, and selectors on the left-hand side tell the elements they select to inherit attributes from the attribute class. Example:
.foo, .bar { font-weight : bold; font-size : 2em; /* attribute class A */}
.foo { color : green; /* attribute class B */}
When an element is given the attribute class="foo", it is useful to think of it not as inheriting attributes from class .foo, but from attribute class A and attribute class B. I.e., the inheritance graph is one level deep, with elements deriving from attribute classes, and the selectors specifying where the edges go, and determining precedence when there are competing attributes (similar to method resolution order).
The practical implication for programming is this. Say you have the style sheet given above, and want to add a new class .baz, where it should have the same font-size as .foo. The naive solution would be this:
.foo, .bar { font-weight : bold; font-size : 2em; /* attribute class A */}
.foo { color : green; /* attribute class B */}
.baz { font-size : 2em; /* attribute class C, hidden dependency! */}
Any time I have to type something twice I get so mad! Not only do I have to write it twice, now I have no way of programatically indicating that .foo and .baz should have the same font-size, and I've created a hidden dependency! My above paradigm would suggest that I should abstract out the font-size attribute from attribute class A:
.foo, .bar, .baz { font-size : 2em; /* attribute base class for A */}
.foo, .bar { font-weight : bold; /* attribute class A */}
.foo { color : green; /* attribute class B */}
The main complaint here is that now I have to retype every selector from attribute class A again to specify that the elements they should select should also inherit attributes from attribute base class A. Still, the alternatives are to have to remember to edit every attribute class where there are hidden dependencies each time something changes, or to use a third party tool. The first option makes god laugh, the second makes me want to kill myself.
That's not possible in CSS.
The only thing supported in CSS is being more specific than another rule:
span { display:inline }
span.myclass { background: red }
A span with class "myclass" will have both properties.
Another way is by specifying two classes:
<div class="something else">...</div>
The style of "else" will override (or add) the style of "something"
As others have said, you can add multiple classes to an element.
But that's not really the point. I get your question about inheritance. The real point is that inheritance in CSS is done not through classes, but through element hierarchies. So to model inherited traits you need to apply them to different levels of elements in the DOM.
While direct inheritance isn't possible.
It is possible to use a class (or id) for a parent tag and then use CSS combinators to alter child tag behaviour from it's heirarchy.
p.test{background-color:rgba(55,55,55,0.1);}
p.test > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
<p class="test"><span>One <span>possible <span>solution <span>is <span>using <span>multiple <span>nested <span>tags</span></span></span></span></span></span></span></span></p>
I wouldn't suggest using so many spans like the example, however it's just a proof of concept. There are still many bugs that can arise when trying to apply CSS in this manner. (For example altering text-decoration types).
I was looking for that like crazy too and I just figured it out by trying different things :P... Well you can do it like that:
composite.something, composite.else
{
blblalba
}
It suddenly worked for me :)
In specific circumstances you can do a "soft" inheritance:
.composite
{
display:inherit;
background:inherit;
}
.something { display:inline }
.else { background:red }
This only works if you are adding the .composite class to a child element. It is "soft" inheritance because any values not specified in .composite are not inherited obviously. Keep in mind it would still be less characters to simply write "inline" and "red" instead of "inherit".
Here is a list of properties and whether or not they do this automatically:
https://www.w3.org/TR/CSS21/propidx.html
Less and Sass are CSS pre-processors which extend CSS language in valuable ways. Just one of many improvements they offer is just the option you're looking for. There are some very good answers with Less and I will add Sass solution.
Sass has extend option which allows one class to be fully extended to another one. More about extend you can read in this article
I think this one is a better solution:
[class*=“button-“] {
/* base button properties */
}
.button-primary { ... }
.button-plain { ... }
Actually what you're asking for exists - however it's done as add-on modules. Check out this question on Better CSS in .NET for examples.
Check out Larsenal's answer on using LESS to get an idea of what these add-ons do.
CSS doesn't really do what you're asking. If you want to write rules with that composite idea in mind, you may want to check out compass. It's a stylesheet framework which looks similar to the already mentioned Less.
It lets you do mixins and all that good business.
For those who are not satisfied with the mentioned (excellent) posts, you can use your programming skills to make a variable (PHP or whichever) and have it store the multiple class names.
That's the best hack I could come up with.
<style>
.red { color: red; }
.bold { font-weight: bold; }
</style>
<? define('DANGERTEXT','red bold'); ?>
Then apply the global variable to the element you desire rather than the class names themselves
<span class="<?=DANGERTEXT?>"> Le Champion est Ici </span>
Have a look at CSS compose:
https://bambielli.com/til/2017-08-11-css-modules-composes/
according to them:
.serif-font {
font-family: Georgia, serif;
}
.display {
composes: serif-font;
font-size: 30px;
line-height: 35px;
}
I use it in my react project.
If you want a more powerful text preprocessor than LESS, check out PPWizard:
http://dennisbareis.com/ppwizard.htm
Warning the website is truly hideous and there's a small learning curve, but it's perfect for building both CSS and HTML code via macros. I've never understood why more web coders don't use it.
You can achieve what you want if you preprocess your .css files through php.
...
$something='color:red;'
$else='display:inline;';
echo '.something {'. $something .'}';
echo '.else {'. $something .'}';
echo '.somethingelse {'. $something .$else '}';
...

CSS to prevent child element from inheriting parent styles [duplicate]

This question already has answers here:
Closed 12 years ago.
Possible Duplicate:
How do I prevent CSS inheritance?
Is there a way to declare the CSS property of an element such that it will not affect any of its children or is there a way to declare CSS of an element to implement just the style specified and not inherit any of the style declared for its parents?
A quick example
HTML:
<body>
<div id="container">
<form>
<div class="sub">Content of the paragraph
<div class='content'>Content of the span</div>
</div>
</form>
</div>
</body>
CSS:
form div {font-size: 12px; font-weight: bold;}
div.content
{
/* Can anything go here? */
}
Under normal circumstances one would expect the text block "Content of the paragraph" and "Content of the span" will both be 12px and bold.
Is there a property to include in the CSS above in the "div.content" block that will prevent it from inheriting the declaration in the "#container form div" block to limit the style to just "content of the paragraph" and spare "Content of the span" including any other children div?
If you are wondering why, well, I created a particular CSS file that gives all the forms on my project a particular feel and the div elements under the form all inherit the feel. No problem. But inside the form I want to use Flexigrid but flexigrid inherits the style and it just looks useless. If I use flexigrid outside the form and such it won't inherit the forms css, then it looks great. Otherwise it just looks terrible.
Unfortunately, you're out of luck here.
There is inherit to copy a certain value from a parent to its children, but there is no property the other way round (which would involve another selector to decide which style to revert).
You will have to revert style changes manually:
div { color: green; }
form div { color: red; }
form div div.content { color: green; }
If you have access to the markup, you can add several classes to style precisely what you need:
form div.sub { color: red; }
form div div.content { /* remains green */ }
Edit: The CSS Working Group is up to something:
div.content {
all: revert;
}
No idea, when or if ever this will be implemented by browsers.
Edit 2: As of March 2015 all modern browsers but Safari and IE/Edge have implemented it: https://twitter.com/LeaVerou/status/577390241763467264 (thanks, #Lea Verou!)
Edit 3: default was renamed to revert.
Can't you style the forms themselves? Then, style the divs accordingly.
form
{
/* styles */
}
You can always overrule inherited styles by making it important:
form
{
/* styles */ !important
}
CSS rules are inherited by default - hence the "cascading" name. To get what you want you need to use !important:
form div
{
font-size: 12px;
font-weight: bold;
}
div.content
{
// any rule you want here, followed by !important
}

Can a CSS class inherit one or more other classes?

Is it possible to make a CSS class that "inherits" from another CSS class (or more than one).
For example, say we had:
.something { display:inline }
.else { background:red }
What I'd like to do is something like this:
.composite
{
.something;
.else
}
where the ".composite" class would both display inline and have a red background
There are tools like LESS, which allow you to compose CSS at a higher level of abstraction similar to what you describe.
Less calls these "Mixins"
Instead of
/* CSS */
#header {
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
border-radius: 8px;
}
#footer {
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
border-radius: 8px;
}
You could say
/* LESS */
.rounded_corners {
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
border-radius: 8px;
}
#header {
.rounded_corners;
}
#footer {
.rounded_corners;
}
You can add multiple classes to a single DOM element, e.g.
<div class="firstClass secondClass thirdclass fourthclass"></div>
Rules given in later classes (or which are more specific) override. So the fourthclass in that example kind of prevails.
Inheritance is not part of the CSS standard.
Yes, but not exactly with that syntax.
.composite,
.something { display:inline }
.composite,
.else { background:red }
Keep your common attributes together and assign specific (or override) attributes again.
/* ------------------------------------------------------------------------------ */
/* Headings */
/* ------------------------------------------------------------------------------ */
h1, h2, h3, h4
{
font-family : myfind-bold;
color : #4C4C4C;
display:inline-block;
width:900px;
text-align:left;
background-image: linear-gradient(0, #F4F4F4, #FEFEFE);/* IE6 & IE7 */
}
h1
{
font-size : 300%;
padding : 45px 40px 45px 0px;
}
h2
{
font-size : 200%;
padding : 30px 25px 30px 0px;
}
The SCSS way for the given example, would be something like:
.something {
display: inline
}
.else {
background: red
}
.composite {
#extend .something;
#extend .else;
}
More info, check the sass basics
An element can take multiple classes:
.classOne { font-weight: bold; }
.classTwo { font-famiy: verdana; }
<div class="classOne classTwo">
<p>I'm bold and verdana.</p>
</div>
And that's about as close as you're going to get unfortunately. I'd love to see this feature, along with class-aliases someday.
No you can't do something like
.composite
{
.something;
.else
}
This are no "class" names in the OO sense. .something and .else are just selectors nothing more.
But you can either specify two classes on an element
<div class="something else">...</div>
or you might look into another form of inheritance
.foo {
background-color: white;
color: black;
}
.bar {
background-color: inherit;
color: inherit;
font-weight: normal;
}
<div class="foo">
<p class="bar">Hello, world</p>
</div>
Where the paragraphs backgroundcolor and color are inherited from the settings in the enclosing div which is .foo styled. You might have to check the exact W3C specification. inherit is default for most properties anyway but not for all.
I ran into this same problem and ended up using a JQuery solution to make it seem like a class can inherit other classes.
<script>
$(function(){
$(".composite").addClass("something else");
});
</script>
This will find all elements with the class "composite" and add the classes "something" and "else" to the elements. So something like <div class="composite">...</div> will end up like so: <div class="composite something else">...</div>
You can do is this
CSS
.car {
font-weight: bold;
}
.benz {
background-color: blue;
}
.toyota {
background-color: white;
}
HTML
<div class="car benz">
<p>I'm bold and blue.</p>
</div>
<div class="car toyota">
<p>I'm bold and white.</p>
</div>
Don't forget:
div.something.else {
// will only style a div with both, not just one or the other
}
You can use the converse approach to achieve the same result - start from the composite and then remove styling using the unset keyword. For example, if you start with the following sample composition:
.composite {
color: red;
margin-left: 50px;
background-color: green
}
you can then increase selector specificity to selectively remove styles using unset:
.composite.no-color {
color: unset
}
.composite.no-margin-left {
margin-left: unset
}
.composite.no-background-color {
background-color: unset
}
Here is a JSFiddle demonstrating this approach.
One benefit of this approach is that because the specificity of the compound selectors is higher than the composite itself, you do not need all of the combinations of classes to achieve the desired results for multiple combinations:
/* Multi-unset compound selector combinations, such as the one that follows, ARE NOT NECESSARY because of the higher specificity of each individual compound selectors listed above. This keeps things simple. */
.composite.no-background-color.no-color.no-margin-left {
background-color: unset;
color: unset;
margin-left: unset
}
Furthermore, at 96% support for the unset keyword, browser coverage is excellent.
Perfect timing: I went from this question to my email, to find an article about Less, a Ruby library that among other things does this:
Since super looks just like footer, but with a different font, I'll use Less's class inclusion technique (they call it a mixin) to tell it to include these declarations too:
#super {
#footer;
font-family: cursive;
}
In Css file:
p.Title
{
font-family: Arial;
font-size: 16px;
}
p.SubTitle p.Title
{
font-size: 12px;
}
I realize this question is now very old but, here goes nothin!
If the intent is to add a single class that implies the properties of multiple classes, as a native solution, I would recommend using JavaScript/jQuery (jQuery is really not necessary but certainly useful)
If you have, for instance .umbrellaClass that "inherits" from .baseClass1 and .baseClass2 you could have some JavaScript that fires on ready.
$(".umbrellaClass").addClass("baseClass1");
$(".umbrellaClass").addClass("baseClass2");
Now all elements of .umbrellaClass will have all the properties of both .baseClasss. Note that, like OOP inheritance, .umbrellaClass may or may not have its own properties.
The only caveat here is to consider whether there are elements being dynamically created that won't exist when this code fires, but there are simple ways around that as well.
Sucks css doesn't have native inheritance, though.
Unfortunately, CSS does not provide 'inheritance' in the way that programming languages like C++, C# or Java do. You can't declare a CSS class an then extend it with another CSS class.
However, you can apply more than a single class to an tag in your markup ... in which case there is a sophisticated set of rules that determine which actual styles will get applied by the browser.
<span class="styleA styleB"> ... </span>
CSS will look for all the styles that can be applied based on what your markup, and combine the CSS styles from those multiple rules together.
Typically, the styles are merged, but when conflicts arise, the later declared style will generally win (unless the !important attribute is specified on one of the styles, in which case that wins). Also, styles applied directly to an HTML element take precedence over CSS class styles.
Don't think of css classes as object oriented classes, think of them as merely a tool among other selectors to specify which attribute classes an html element is styled by. Think of everything between the braces as the attribute class, and selectors on the left-hand side tell the elements they select to inherit attributes from the attribute class. Example:
.foo, .bar { font-weight : bold; font-size : 2em; /* attribute class A */}
.foo { color : green; /* attribute class B */}
When an element is given the attribute class="foo", it is useful to think of it not as inheriting attributes from class .foo, but from attribute class A and attribute class B. I.e., the inheritance graph is one level deep, with elements deriving from attribute classes, and the selectors specifying where the edges go, and determining precedence when there are competing attributes (similar to method resolution order).
The practical implication for programming is this. Say you have the style sheet given above, and want to add a new class .baz, where it should have the same font-size as .foo. The naive solution would be this:
.foo, .bar { font-weight : bold; font-size : 2em; /* attribute class A */}
.foo { color : green; /* attribute class B */}
.baz { font-size : 2em; /* attribute class C, hidden dependency! */}
Any time I have to type something twice I get so mad! Not only do I have to write it twice, now I have no way of programatically indicating that .foo and .baz should have the same font-size, and I've created a hidden dependency! My above paradigm would suggest that I should abstract out the font-size attribute from attribute class A:
.foo, .bar, .baz { font-size : 2em; /* attribute base class for A */}
.foo, .bar { font-weight : bold; /* attribute class A */}
.foo { color : green; /* attribute class B */}
The main complaint here is that now I have to retype every selector from attribute class A again to specify that the elements they should select should also inherit attributes from attribute base class A. Still, the alternatives are to have to remember to edit every attribute class where there are hidden dependencies each time something changes, or to use a third party tool. The first option makes god laugh, the second makes me want to kill myself.
That's not possible in CSS.
The only thing supported in CSS is being more specific than another rule:
span { display:inline }
span.myclass { background: red }
A span with class "myclass" will have both properties.
Another way is by specifying two classes:
<div class="something else">...</div>
The style of "else" will override (or add) the style of "something"
As others have said, you can add multiple classes to an element.
But that's not really the point. I get your question about inheritance. The real point is that inheritance in CSS is done not through classes, but through element hierarchies. So to model inherited traits you need to apply them to different levels of elements in the DOM.
While direct inheritance isn't possible.
It is possible to use a class (or id) for a parent tag and then use CSS combinators to alter child tag behaviour from it's heirarchy.
p.test{background-color:rgba(55,55,55,0.1);}
p.test > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
<p class="test"><span>One <span>possible <span>solution <span>is <span>using <span>multiple <span>nested <span>tags</span></span></span></span></span></span></span></span></p>
I wouldn't suggest using so many spans like the example, however it's just a proof of concept. There are still many bugs that can arise when trying to apply CSS in this manner. (For example altering text-decoration types).
I was looking for that like crazy too and I just figured it out by trying different things :P... Well you can do it like that:
composite.something, composite.else
{
blblalba
}
It suddenly worked for me :)
In specific circumstances you can do a "soft" inheritance:
.composite
{
display:inherit;
background:inherit;
}
.something { display:inline }
.else { background:red }
This only works if you are adding the .composite class to a child element. It is "soft" inheritance because any values not specified in .composite are not inherited obviously. Keep in mind it would still be less characters to simply write "inline" and "red" instead of "inherit".
Here is a list of properties and whether or not they do this automatically:
https://www.w3.org/TR/CSS21/propidx.html
Less and Sass are CSS pre-processors which extend CSS language in valuable ways. Just one of many improvements they offer is just the option you're looking for. There are some very good answers with Less and I will add Sass solution.
Sass has extend option which allows one class to be fully extended to another one. More about extend you can read in this article
I think this one is a better solution:
[class*=“button-“] {
/* base button properties */
}
.button-primary { ... }
.button-plain { ... }
Actually what you're asking for exists - however it's done as add-on modules. Check out this question on Better CSS in .NET for examples.
Check out Larsenal's answer on using LESS to get an idea of what these add-ons do.
CSS doesn't really do what you're asking. If you want to write rules with that composite idea in mind, you may want to check out compass. It's a stylesheet framework which looks similar to the already mentioned Less.
It lets you do mixins and all that good business.
For those who are not satisfied with the mentioned (excellent) posts, you can use your programming skills to make a variable (PHP or whichever) and have it store the multiple class names.
That's the best hack I could come up with.
<style>
.red { color: red; }
.bold { font-weight: bold; }
</style>
<? define('DANGERTEXT','red bold'); ?>
Then apply the global variable to the element you desire rather than the class names themselves
<span class="<?=DANGERTEXT?>"> Le Champion est Ici </span>
Have a look at CSS compose:
https://bambielli.com/til/2017-08-11-css-modules-composes/
according to them:
.serif-font {
font-family: Georgia, serif;
}
.display {
composes: serif-font;
font-size: 30px;
line-height: 35px;
}
I use it in my react project.
If you want a more powerful text preprocessor than LESS, check out PPWizard:
http://dennisbareis.com/ppwizard.htm
Warning the website is truly hideous and there's a small learning curve, but it's perfect for building both CSS and HTML code via macros. I've never understood why more web coders don't use it.
You can achieve what you want if you preprocess your .css files through php.
...
$something='color:red;'
$else='display:inline;';
echo '.something {'. $something .'}';
echo '.else {'. $something .'}';
echo '.somethingelse {'. $something .$else '}';
...

Resources