as the question suggested, I want to use custom css colors (with --color*) inside a lighten/darken function. The reason is that I have an Ionic application and I want to change the theme colors dynamically, something like this:
--ion-color-primary: #fff;
--ion-color-primary-rgb: 255, 255, 255;
--ion-color-primary-contrast: #000);
--ion-color-primary-contrast-rgb: 0, 0, 0;
--ion-color-primary-shade: darken(var(--ion-color-primary, 30);
--ion-color-primary-tint: lighten(var(--ion-color-primary, 30);
I am receiving the primary and primary-contrast css properties from other place and I want to be able to set the shade and tint dynamically based on them. With the code above, I received an error saying $color: var(--ion-color-primary) is not a color.
Code snipper
There is a breaking change in Sass since v3.5.0 where you need to write your sass variables and functions within interpolation.
To provide maximum compatibility with plain CSS, more recent versions of Sass require SassScript expressions in custom property values to be written within interpolation. Interpolation will also work for older Sass versions, and so is recommended for all stylesheets.*
Therefore your code should look like this:
$primary: aqua;
--ion-color-primary-shade: #{darken($primary, 30%)};
--ion-color-primary-tint: #{lighten($primary, 30%)};
For the best effect to achieve consider using scale-color() instead of darken/lighten:
The lighten() function increases lightness by a fixed amount, which is often not the desired effect. To make a color a certain percentage lighter than it was before, use scale() instead.**
$primary: aqua;
--ion-color-primary-shade: #{scale-color($primary, $lightness: -30%)};
--ion-color-primary-tint: #{scale-color($primary, $lightness: 30%)};
*For more info about sass interpolation see https://sass-lang.com/documentation/breaking-changes/css-vars.
**For more details on scale-color: https://sass-lang.com/documentation/modules/color#scale
I am trying to change a variable's value in "../myStyle.scss" file from myComponent.ts . I read that it is impossible to achieve it because sass file are compiled into css by the sass pre-processor and the variable disapears. Isn't there a way to work this around.
My variable is called $theme.
And I want to change it's value.
$theme: #5A352A;
and I want it to become $theme: #ffffff; when the user clicks
You have to work in a different way.
Basically when you compile the angular app , it will generate a css file where it substitute the variable with the value , wherever you used it.
So if you want to achieve a color change you have to create a other variable and other classes and swipe it in your class attributes (this is one way, check also ngStyle and ngClass in angular reference).
For example white-theme/dark-theme (the most common case).
variables -> $black: #00000; $white: #ffffff
Example classes:
.body-dark {
background-color: $black;
}
.body-white {
background-color: $white;
}
and swipe the classes in the html elements.
setDark(){
document.getElementById("bodyId").setAttribute("class","body-dark ")
}
the same for white.
I am using Angular5 with sass v1.3.2.
I want to be able to change a color that is used extensively in the scss files of my single page app in runtime (not by compiling new files).
The color is defined globally in my _variables.css as:
$brand: #123123;
And for example used as:
h1 {
color: $brand;
}
I learned that I can modify the color if I am using CSS variables such as:
# CSS
:root {
--brand: #123123
}
#JS
document.documentElement.style.setProperty('--brand', '#456456');
# OR
document.querySelector(':root').style.setProperty('--brand', '#456456');
However to be able to do that using SCSS, I needed to use css-vars mixin as such:
$brand: #123123;
:root {
#include css-vars((
--brand: #{$brand},
));
}
And use it as:
h1 {
color: var(--brand);
}
Two problems:
Actually, still --brand is not showing at root.
Also, the CSS generated in <script type="text/css"> by angular-cli does not have --brand anywhere, it is actually compiling the CSS variable into #123123 so the output is:
h1 {
color: #123123;
}
Any ideas about how can I achieve changing a global color in runtime? Or how to get my CSS in :root and then how to get SASS to not compile it?
UPDATE
As #JonUleis has showed, there is no need for using css-var. Now the var --brand shows in the DOM at :root.
However, now color: var(--brand); line still does not show in the CSS, and h1 doesn't have a color style at all.
After updating node-sass to the latest 4.9.0 from 4.8.3, it worked great.
You're likely on an outdated version of node-sass that wasn't yet compatible with the syntax for CSS custom properties.
Here's your example code compiling successfully using Sassmeister without using the css-vars mixin:
EDIT: Achieve this approach without using #mixin and #include
Currently I'm using Sass as my CSS precompiler for a large and brand new project. I admit it, I really liked the idea behind this tools and it becomes more usable when you want to use it with #mixin functions.
I want to use Sass more quickly. My thought is, assign aliases to variables and just use it in CSS declaration. Consider the following code blocks.
$backgroundColor: #F1F2F2;
body {
background: $backgroundColor;
}
works fine in Sass. But I want to achieve,
$backgroundColor: "background: #F1F2F2";
body {
$backgroundColor;
}
This block returns error in Sass. Any idea, or is it possible to use Sass in this way?
#mixin backgroundColor {
background: #F1F2F2;
}
body {
#include backgroundColor;
}
Should work.
I'm not so familiar with SASS (it's great, though) and I don't have any idea whether you can assign a property name as the value of a variable but what might be wrong in your way of shortening may be a data type issue. Since property names and values do not seem to be single/double quoted strings (and since you use quotes) this situation might confuse SASS. I think you should give the below pattern a try:
$backgroundColor: background + : + #F1F2F2;
body {
$backgroundColor;
}
I’m working on a CSS file that is quite long. I know that the client could ask for changes to the color scheme, and was wondering: is it possible to assign colors to variables, so that I can just change a variable to have the new color applied to all elements that use it?
Please note that I can’t use PHP to dynamically change the CSS file.
CSS supports this natively with CSS Variables.
Example CSS file
:root {
--main-color:#06c;
}
#foo {
color: var(--main-color);
}
For a working example, please see this JSFiddle (the example shows one of the CSS selectors in the fiddle has the color hard coded to blue, the other CSS selector uses CSS variables, both original and current syntax, to set the color to blue).
Manipulating a CSS variable in JavaScript/client side
document.body.style.setProperty('--main-color',"#6c0")
Support is in all the modern browsers
Firefox 31+, Chrome 49+, Safari 9.1+, Microsoft Edge 15+ and Opera 36+ ship with native support for CSS variables.
People keep upvoting my answer, but it's a terrible solution compared to the joy of sass or less, particularly given the number of easy to use gui's for both these days. If you have any sense ignore everything I suggest below.
You could put a comment in the css before each colour in order to serve as a sort of variable, which you can change the value of using find/replace, so...
At the top of the css file
/********************* Colour reference chart****************
*************************** comment ********* colour ********
box background colour bbg #567890
box border colour bb #abcdef
box text colour bt #123456
*/
Later in the CSS file
.contentBox {background: /*bbg*/#567890; border: 2px solid /*bb*/#abcdef; color:/*bt*/#123456}
Then to, for example, change the colour scheme for the box text you do a find/replace on
/*bt*/#123456
Yeeeaaahhh.... you can now use var() function in CSS.....
The good news is you can change it using JavaScript access, which will change globally as well...
But how to declare them...
It's quite simple:
For example, you wanna assign a #ff0000 to a var(), just simply assign it in :root, also pay attention to --:
:root {
--red: #ff0000;
}
html, body {
background-color: var(--red);
}
The good things are the browser support is not bad, also don't need to be compiled to be used in the browser like LESS or SASS...
Also, here is a simple JavaScript script, which changes the red value to blue:
const rootEl = document.querySelector(':root');
root.style.setProperty('--red', 'blue');
CSS itself doesn't use variables. However, you can use another language like SASS to define your styling using variables, and automatically produce CSS files, which you can then put up on the web. Note that you would have to re-run the generator every time you made a change to your CSS, but that isn't so hard.
You can try CSS3 variables:
body {
--fontColor: red;
color: var(--fontColor);
}
There's no easy CSS only solution. You could do this:
Find all instances of background-color and color in your CSS file and create a class name for each unique color.
.top-header { color: #fff; }
.content-text { color: #f00; }
.bg-leftnav { background-color: #fff; }
.bg-column { background-color: #f00; }
Next go through every single page on your site where color was involved and add the appropriate classes for both color and background color.
Last, remove any references of colors in your CSS other than your newly created color classes.
The 'Less' Ruby Gem for CSS looks awesome.
http://lesscss.org/
Yes, in near future (i write this in june 2012) you can define native css variables, without using less/sass etc ! The Webkit engine just implemented first css variable rules, so cutting edge versions of Chrome and Safari are already to work with them. See the Official Webkit (Chrome/Safari) development log with a onsite css browser demo.
Hopefully we can expect widespread browser support of native css variables in the next few months.
Do not use css3 variables due to support.
I would do the following if you want a pure css solution.
Use color classes with semenatic names.
.bg-primary { background: #880000; }
.bg-secondary { background: #008800; }
.bg-accent { background: #F5F5F5; }
Separate the structure from the skin (OOCSS)
/* Instead of */
h1 {
font-size: 2rem;
line-height: 1.5rem;
color: #8000;
}
/* use this */
h1 {
font-size: 2rem;
line-height: 1.5rem;
}
.bg-primary {
background: #880000;
}
/* This will allow you to reuse colors in your design */
Put these inside a separate css file to change as needed.
Sure can, sort of, thanks to the wonderful world of multiple classes, can do this:
.red {color:red}
.blackBack {background-color: black}
but I often end up combining them anyway like this:
.highlight {color:red, background-color: black}
I know the semantic police will be all over you, but it works.
I'm not clear on why you can't use PHP. You could then simply add and use variables as you wish, save the file as a PHP file and link to that .php file as the style sheet instead of the .css file.
It doesn't have to be PHP, but you get what I mean.
When we want programming stuff, why not use a programming language until CSS (maybe) supports things like variables?
Also, check out Nicole Sullivan's Object-oriented CSS.
You can group selectors:
#selector1, #selector2, #selector3 { color: black; }
You could pass the CSS through javascript and replace all instances of COLOUR1 with a certain color (basically regex it) and provide a backup stylesheet incase the end user has JS turned off
dicejs.com (formally cssobjs) is a client-side version of SASS. You can set variables in your CSS (stored in json formatted CSS) and re-use your color variables.
//create the CSS JSON object with variables and styles
var myCSSObjs = {
cssVariables : {
primaryColor:'#FF0000',
padSmall:'5px',
padLarge:'$expr($padSmall * 2)'
}
'body' : {padding:'$padLarge'},
'h1' : {margin:'0', padding:'0 0 $padSmall 0'},
'.pretty' : {padding:'$padSmall', margin:'$padSmall', color:'$primaryColor'}
};
//give your css objects a name and inject them
$.cssObjs('myStyles',myCSSObjs).injectStyles();
And here is a link to a complete downloadable demo which is a little more helpful then their documentation : dicejs demo
EDIT: This answer is no longer current. You should use CSS variables now.
Consider using SCSS. It's full compatible with CSS syntax, so a valid CSS file is also a valid SCSS file. This makes migration easy, just change the suffix. It has numerous enhancements, the most useful being variables and nested selectors.
You need to run it through a pre-processor to convert it to CSS before shipping it to the client.
I've been a hardcore CSS developer for many years now, but since forcing myself to do a project in SCSS, I now won't use anything else.
If you have Ruby on your system you can do this:
http://unixgods.org/~tilo/Ruby/Using_Variables_in_CSS_Files_with_Ruby_on_Rails.html
This was made for Rails, but see below for how to modify it to run it stand alone.
You could use this method independently from Rails, by writing a small Ruby wrapper script
which works in conjunction with site_settings.rb and takes your CSS-paths into account, and
which you can call every time you want to re-generate your CSS (e.g. during site startup)
You can run Ruby on pretty much any operating system, so this should be fairly platform independent.
e.g. wrapper: generate_CSS.rb (run this script whenever you need to generate your CSS)
#/usr/bin/ruby # preferably Ruby 1.9.2 or higher
require './site_settings.rb' # assuming your site_settings file is on the same level
CSS_IN_PATH = File.join( PATH-TO-YOUR-PROJECT, 'css-input-files')
CSS_OUT_PATH = File.join( PATH-TO-YOUR-PROJECT, 'static' , 'stylesheets' )
Site.generate_CSS_files( CSS_IN_PATH , CSS_OUT_PATH )
the generate_CSS_files method in site_settings.rb then needs to be modified like this:
module Site
# ... see above link for complete contents
# Module Method which generates an OUTPUT CSS file *.css for each INPUT CSS file *.css.in we find in our CSS directory
# replacing any mention of Color Constants , e.g. #SomeColor# , with the corresponding color code defined in Site::Color
#
# We will only generate CSS files if they are deleted or the input file is newer / modified
#
def self.generate_CSS_files(input_path = File.join( Rails.root.to_s , 'public' ,'stylesheets') ,
output_path = File.join( Rails.root.to_s , 'public' ,'stylesheets'))
# assuming all your CSS files live under "./public/stylesheets"
Dir.glob( File.join( input_path, '*.css.in') ).each do |filename_in|
filename_out = File.join( output_path , File.basename( filename_in.sub(/.in$/, '') ))
# if the output CSS file doesn't exist, or the the input CSS file is newer than the output CSS file:
if (! File.exists?(filename_out)) || (File.stat( filename_in ).mtime > File.stat( filename_out ).mtime)
# in this case, we'll need to create the output CSS file fresh:
puts " processing #{filename_in}\n --> generating #{filename_out}"
out_file = File.open( filename_out, 'w' )
File.open( filename_in , 'r' ).each do |line|
if line =~ /^\s*\/\*/ || line =~ /^\s+$/ # ignore empty lines, and lines starting with a comment
out_file.print(line)
next
end
while line =~ /#(\w+)#/ do # substitute all the constants in each line
line.sub!( /#\w+#/ , Site::Color.const_get( $1 ) ) # with the color the constant defines
end
out_file.print(line)
end
out_file.close
end # if ..
end
end # def self.generate_CSS_files
end # module Site
Not PHP I'm afraid, but Zope and Plone use something similar to SASS called DTML to achieve this. It's incredibly useful in CMS's.
Upfront Systems has a good example of its use in Plone.
If you write the css file as an xsl template, you could read color values from a simple xml file. Then create the css with an xslt processor.
colors.xml:
<?xml version="1.0"?>
<colors>
<background>#ccc</background>
</colors>
styles.xsl:
<?xml version="1.0"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text" version="1.0" encoding="iso-8859-1"/>
<xsl:template match="/">body {
background-color: <xsl:value-of select="/colors/background" />;
}
</xsl:template>
</xsl:stylesheet>
Command to render css: xsltproc -o styles.css styles.xsl colors.xml
styles.css:
body {
background-color: #ccc;
}
It’s not possible with CSS alone.
You can do it with JavaScript and LESS using less.js, which will render LESS variables into CSS live, but it’s for development only and adds too much overhead for real-life use.
The closest you can come with CSS is to use an attribute substring selector like this:
[id*="colvar-"] {
color: #f0c69b;
}
and set the ids of all your elements that you want to be adjusted to names starting with colvar-, such as colvar-header. Then when you change the color, all the ID styles are updated. That’s as close as you can get with CSS alone.