I want to include a value from another class - and use this for something different:
I have this class:
.sourceClass {
color: red;
}
And I have this class:
.destinationClass {
border-color: ###should be the color from .sourceClass => red
}
is this possible? And how can I do that?
You tagged your post with "Sass". Are you using the Sass/SCSS preprocessor? If so, you'd declare and use a variable like this:
$myColor: red;
.sourceClass { color: $myColor; }
.destinationClass { border-color: $myColor; }
If you're not using Sass, you can read about native CSS variables - which are currently working in Firefox and Chrome, but not IE/Edge.
Lastly, there is a possible solution supported in all current browsers, which would be applicable depending on your DOM hierarchy: currentColor.
If your .destinationClass is a child of .sourceClass, and therefore is inheriting color: red, you could simply use border-color: currentColor to take that color and use it as the border color.
Hope this helps!
Related
I'm currently developing a web application in Outsystems in which I have the need to customize the CSS, in which I'm using variables. I need to guarantee the app works cross-browser, including in Internet Explorer. IE doesn't support CSS variables, as you can see in the picture below from this source.
Since I have to use CSS variables, is there any workaround for the usage of variables in IE?
Yes there is a way, the same way you make any css compatible: use a specific css fallback that is supported by the browser.
body {
--text-color: red;
}
body {
color: red; /* default supported fallback style */
color: var(--text-color); /* will not be used by any browser that doesn't support it, and will default to the previous fallback */
}
This solution is incredibly redundant and 'almost' defeats the purpose of css variables....BUT it is necessary for browser compatibility. Doing this would essentially make the css variables useless but I implore you to still use them because it will serve as an important reminder to the fact that these values are referenced elsewhere and need to be updated in all cases, otherwise you forget to update every related occurrence of 'color' and then you have inconsistent styling because relevant css values are out of sync. The variable will serve more as a comment but a very important one.
There is a polyfill, which enables almost complete support for CSS variables in IE11:
https://github.com/nuxodin/ie11CustomProperties
(i am the author)
The script makes use of the fact that IE has minimal custom properties support where properties can be defined and read out with the cascade in mind.
.myEl {-ie-test:'aaa'} // only one dash allowed! "-"
then read it in javascript:
getComputedStyle( querySelector('.myEl') )['-ie-test']
From the README:
Features
handles dynamic added html-content
handles dynamic added , -elements
chaining --bar:var(--foo)
fallback var(--color, blue)
:focus, :target, :hover
js-integration:
style.setProperty('--x','y')
style.getPropertyValue('--x')
getComputedStyle(el).getPropertyValue('--inherited')
Inline styles: <div ie-style="--color:blue"...
cascade works
inheritance works
under 3k (min+gzip) and dependency-free
Demo:
https://rawcdn.githack.com/nuxodin/ie11CustomProperties/b851ec2b6b8e336a78857b570d9c12a8526c9a91/test.html
In case someone comes across this, has a similar issue where I had it set like this.
a {
background: var(--new-color);
border-radius: 50%;
}
I added the background colour before the variable so if that didn't load it fell back on the hex.
a {
background: #3279B8;
background: var(--new-color);
border-radius: 50%;
}
Yes, so long as you're processing root-level custom properties (IE9+).
GitHub: https://github.com/jhildenbiddle/css-vars-ponyfill
NPM: https://www.npmjs.com/package/css-vars-ponyfill
Demo: https://codepen.io/jhildenbiddle/pen/ZxYJrR
From the README:
Features
Client-side transformation of CSS custom properties to static values
Live updates of runtime values in both modern and legacy browsers
Transforms <link>, <style>, and #import CSS
Transforms relative url() paths to absolute URLs
Supports chained and nested var() functions
Supports var() function fallback values
Supports web components / shadow DOM CSS
Watch mode auto-updates on <link> and <style> changes
UMD and ES6 module available
TypeScript definitions included
Lightweight (6k min+gzip) and dependency-free
Limitations
Custom property support is limited to :root and :host declarations
The use of var() is limited to property values (per W3C specification)
Here are a few examples of what the library can handle:
Root-level custom properties
:root {
--a: red;
}
p {
color: var(--a);
}
Chained custom properties
:root {
--a: var(--b);
--b: var(--c);
--c: red;
}
p {
color: var(--a);
}
Nested custom properties
:root {
--a: 1em;
--b: 2;
}
p {
font-size: calc(var(--a) * var(--b));
}
Fallback values
p {
font-size: var(--a, 1rem);
color: var(--b, var(--c, var(--d, red)));
}
Transforms <link>, <style>, and #import CSS
<link rel="stylesheet" href="/absolute/path/to/style.css">
<link rel="stylesheet" href="../relative/path/to/style.css">
<style>
#import "/absolute/path/to/style.css";
#import "../relative/path/to/style.css";
</style>
Transforms web components / shadow DOM
<custom-element>
#shadow-root
<style>
.my-custom-element {
color: var(--test-color);
}
</style>
<div class="my-custom-element">Hello.</div>
</custom-element>
For the sake of completeness: w3c specs
Hope this helps.
(Shameless self-promotion: Check)
Make a seperate .css file for your variables. Copy/paste the contents of the variable.css file to the end of your main.css file. Find and replace all the variable names in the main.css file to the hex code for those variables. For example: ctrl-h to find var(--myWhiteVariable) and replace with #111111.
Side note: if you keep the :root{ } in the main.css file and just comment it out, you can use that to track those hex codes later if you want to update your fallback colors.
Another way to do it is declaring colors in a JS file (in my case I'm using react) and then just use the variable you defined in the JS file.
For example:
in globals.js
export const COLORS = {
yellow: '#F4B400',
yellowLight: '#F4C849',
purple: '#7237CC',
purple1: '#A374EB',
}
in your file
import { COLORS } from 'globals'
and then just use COLORS.yellow, COLORS.purple, etc.
body {
--text-color : red; /* --text-color 정의 */
}
body {
color: var(--text-color, red); /* --text-color 정의되지 않으면 red로 대체됨 */
}
body {
color: var(--text-color, var(--text-color-other, blue));
/* --text-color, --text-color-other 가 정의되지 않으면 blue로 대체됨 */
}
There is no way yet in "normal" css but take a look at sass/scss or less.
here is a scss example
$font-stack: Helvetica, sans-serif;
$primary-color: #333;
body {
font: 100% $font-stack;
color: $primary-color;
}
I recommend setting your css variables as sass variables, then using sass interpolation to render the color in your elements.
:root {
--text-color: #123456;
}
$text-color: var(--text-color);
body {
color: #{$text-color};
}
If im not wrong there is a workaround, the CSS #ID Selector. Which should work for IE > 6 I guess.. So you can
.one { };
<div class="one">
should work as
#one {};
<div id="one">
I'm looking into LESS because I definitely see some of their benefits. For instance colour declaration.
One thing I don't understand tho, and maybe I'm not getting the flow right is - why use the following LESS snippet
.radius {
-webkit-border-radius:5px;
-moz-border-radius:5px;
border-radius:5px;
}
.btn-red{
background-color:red;
.radius;
}
.btn-green{
background-color:green;
.radius;
}
...
When we can use the .radius class in the html file right away. I'm left with the impression that LESS will add a ton of duplicate code once it gets compiled.
I'm using the following, which makes more sense. Same with font-size, margins, etc... Aren't classes used in such cases?
<div class="btn-red radius">Cancel</div>
<div class="btn-green radius">Go</div>
The snippet above does not benefit from SASS/LESS capabilities that much. Lets have a closer look and check this SCSS snippet.
// Abstract placeholder.
%radius {
border-radius: 5px;
}
// Put your global styling here.
// I'm assuming that you can alter the markup and have button.btn.btn-green
.btn {
// Color modifier.
&-red {
#extend %radius;
background-color: red;
}
&-green {
#extend %radius;
background-color: green;
}
}
The CSS output will be:
.btn-red, .btn-green {
border-radius: 5px;
}
.btn-red {
background-color: red;
}
.btn-green {
background-color: green;
}
And then you have to pick up Autoprefixer and vendor-prefixes issue is solved once and for all.
Because now, you can just specify the class btn_red or btn_green and all the buttons will automatically have a radius.
Your HTML should contain only the semantics, and styling or classes referring to styling should not be part of it.
That applies to the other classes as well. If for instance, you would rename btn_red to btn_cancel, you have a meaningful classname that you can apply to any kind of cancel button. And in the CSS you can specify that a cancel button is red and a 'Go' button is green, and both have a radius, without needing to modify the HTML at all.
So, the ultimate goal is to have the HTML describe the structure and the CSS describe how that structure should look. And a CSS preprocessor is only their to make a bulky spaghetti-like CSS file more structured.
There are several benefits.
You can use more semantic class names. Rather than encoding style information directly in your class names, (btn-red, radius) you could use a single class that conveys the usage of the style, rather than its contents.
You can avoid repeating yourself.
#radius-size: 5px;
-webkit-border-radius:#radius-size;
-moz-border-radius:#radius-size;
border-radius:#radius-size;
You can parameterize it so that you'd be able to use different radiuses (radii?) in different contexts.
.radius(#radius-size) { ... }
Because there are cases that developer has-no-access or don't-want to change the markup. and the only solution is to include all props from a predefined class.
for example:
you have bootstrap loaded (then you already have .has-success and .has-error classes) and if you want to use HTML5's native form validation using input's :valid and :invalid states, you have to use JavaScript to add/remove success/error classes based on input's states. but with this feature of LESS you can include all props of success/error class inside input's states. the code for this example could be something like this:
#myinput {
&:valid { .has-success; }
&:invalid { .has-error; }
}
I'm trying to create a few dynamics classes width Less css.
The idea is use in html this class:
.color-white{
color: white !important;
}
I created this sintaxis in Less:
.change-color(#which; #color){
.color-#{which}{
color:#color !important;
}
.background-#{which}{
background-color:#color !important;
}
}
So, with this I want to take my idea :D
.change-color(#which: white; #color: white);
But, that is the problem, I have this:
.color-#ffffff{
color:#fff!important
}
.background-#ffffff{
background-color:#fff!important
}
How can I use "white" as string and not as hex color.
Thanks.
Call this way instead:
.change-color(#which: ~'white'; #color: ~'white');
Though I think it would be better to just create a class called .color-red explicitly rather than make things more unreadable for little reason.
So lets say I set the background of 10 elements on the page to #base, then a user lands on the "Foo" page which has the class on the body of the page.
How does one update the #base via a css declaration? I understand that variables are local to a function (or css declaration) but there must be a method to do this! (would make styling alternative pages so easy!)
#base: #00000;
body.foo{
#base = #FFF;
}
LESS is a Preprocessor so...
...it all has to be precompiled into CSS ahead of time. That means all possible class combinations need to be made into valid CSS ahead of time. If you wanted something like this, you would need to do something like the following in your LESS:
LESS
#base: #000000;
.setColorOptions(#className: ~'', #base: #base) {
#classDot: escape(`('#{className}' == '' ? '' : '.')`);
#class: escape(#className);
body#{classDot}#{class} {
someElement {color: #base;}
.someClass {color: #base;}
// etc.
}
}
.setColorOptions();
.setColorOptions(foo, #fff);
.setColorOptions(bar, #ccc);
CSS Output
body someElement {
color: #000000;
}
body .someClass {
color: #000000;
}
body.foo someElement {
color: #ffffff;
}
body.foo .someClass {
color: #ffffff;
}
body.bar someElement {
color: #cccccc;
}
body.bar .someClass {
color: #cccccc;
}
Obviously if there were many elements and a lot of color dependent things going on, this could get big fast. Imagine 100 elements under body with three color variations as above, and you have 300+ lines of CSS, 200+ (two-thirds) of which do not apply to any one page. And this doesn't account for other changes, like background colors, etc. In such a case, it is best to set up different LESS files that import a different set of values for #base and build different style sheets to be loaded on the pages that need it. However, if you are just doing a small subset of color changes to a page, this could be a valid way to go.
There is no way to do that.
LESS has no way to know whether the selector body.foo will apply at compile time.
I have a very wierd question, I dont know wether if its possible in css or not
Suppose I have say 3 different css classes as shown below, as you can see I have a common property of all these classes, I want to declare this color somewhere else and pass a reference to it here, so if next time I want to change the color I can simply change at one place rather than changing in all the 5 classes.
I know that you can use body{}, or a wrapper for this but that would affect the colors of the entire site right ? Is there a way to do this ?
Is this even possible ?
.abc {
color:red;
}
.abc2 {
color:red;
}
.abc3 {
color:red;
}
.abc4 {
color:red;
}
.abc5 {
color:red;
}
The bad news: you can't do it in CSS.
The good news: you can write in a meta-CSS language like LESS, which then processes a LESS file to pure CSS. This is called a "mixin".
In LESS:
#errorColor: red;
.error-color {
color: #errorColor;
}
#error-1 {
.error-color;
}
.all-errors {
.error-color;
}
More info: http://lesscss.org/#-mixins
if you want to declare all of them at a time, you can use:
.abc, .abc2, .abc3, .abc4, .abc5 {
color:red;
}
Or you can declare an additional class & add to all the .abc, .abc2.... & make its color:red;.
This can not be done with CSS, but that is still a very popular thing to do by using a CSS preprocessor such as LESS, SASS, SCSS, or Stylus.
A preprocessor will let you define a variable (say $red = #F00). It will replace the variable in your CSS document with the variable value for you, allowing you to write very DRY and module CSS.
This functionality is referred to as "CSS variables", which is part of the future spec, but not yet implemented on any browsers.
For now, the best way to do this in pure CSS is to declare an additional class for the desired "global", and then add that class to all relevant items.
.abc_global { color: red; }
.abc1 { /* additional styling */ }
.abc2 { /* additional styling */ }
<div class="abc1 abc_global"></div>
<div class="abc2 abc_global"></div>
With LESS
You are able to define that red color once:
.myRedColor {
color:red;
}
Now you can call that red on any CSS styles. Even NESTED styles! It's a wicked tool!
.abc1 {
.myRedColor;
}
.abc2 {
.myRedColor;
}
.abc3 {
.myRedColor;
}
.abc4 {
.myRedColor;
}
NESTED EXAMPLE:
.abc {
.itsEasyAsOneTwoThree{
.myRedColor;
}
}
Now all of our "itsEasyAsOneTwoThree" classes that are properly nested inside of an "abc" class will be assigned the red style. No more remembering those long #867530 color codes :) How cool is that?!
You can also use PostCSS with the plugin postcss-preset-env and support custom properties/variables, then use the :root selector to add global css variables.
:root {
--color-gray: #333333;
--color-white: #ffffff;
--color-black: #000000;
}