When trying to display in CSS the SASS variable that I declared, I don't get the variable itself in the CSS output file, but the value given to the variable.
To be more clear, this is what I get:
SCSS/SASS input
$gray__background: #2d2d2d;
:root {
--gray__background: #{$gray__background};
}
body{
background-color: $gray__background;
}
CSS "output"
:root {
--gray__background: #2d2d2d;
}
body{
background-color: #2d2d2d;
}
That's what I was expecting to get:
CSS "output"
:root {
--gray__background: #2d2d2d;
}
body{
background-color: var(--gray__background);
}
Short story: I want to know if the result in the CSS "auto generated" file background-color: var(--gray__background);, instead of background-color: #2d2d2d; is possible to achieve.
I use the Live Sass Compiler extension for VSCode.
Sorry if my question is a little bit vague. I'm new to coding.
The :root variables are being declared in the SCSS, but are not being used, so they wouldn't show up on the CSS output.
It looks like you'll have to use --gray__background in the SCSS rather than $gray__background so it becomes: background-color: var(--gray__background);
.
Hope this helps.
This question already has answers here:
Is there a way to interpolate CSS variables with url()?
(4 answers)
CSS set background-image by data-image attr
(4 answers)
Closed 3 years ago.
I'm trying to assign the url of background-image dynamically though css from the attributes defined on html tags. But it seems neither attr() nor var() works. I'm avoiding to use javascript because the url might change later so I have to trigger that script manually again.
Is there a better solution for this?
body {
display: flex;
}
.normal, .attr, .var {
flex: 1;
height: 240px;
border: solid 1px #666;
background-size: cover;
}
.normal {
background-image: url("https://picsum.photos/320/240");
}
.attr {
background-image: url(attr(data-bg));
}
.var {
background-image: url(var(--url));
}
<div class="normal"></div>
<div class="attr" data-bg="https://picsum.photos/320/240"></div>
<div class="var" style="--url: 'https://picsum.photos/320/240';"></div>
Even more, I wish I can concatenate the string if it's possible.
.image {
border: solid 1px #666;
width: 320px;
height: 240px;
/* I wish this is possible */
background-image: url("http://www.example.com/images/" attr(data-bg) ".png");
}
<div class="image" data-bg="adorable_cat"></div>
Even if I feel like it would be much easier to do with simply using inline background-image property (especially if you want to concatenate url string). For simple use you can do that like that:
<div class="var" style="--url: url(https://picsum.photos/320/240)"></div>
.var {
background-image: var(--url);
}
For reasons unclear for me, using url(var(--url)); doesn't seem to be working at all (at least at Chrome)
Put an embedded stylesheet in the document's :
<style type="text/css">
.logo
{
background: #FFF url(<?php echo $variable_holding_img_url; ?>);
}
</style>
for more information
enter link description here
How to have dynamic image as CSS background?
I am trying to closely stick to the BEM methodology and I am frequently running into this issue which I feel it is time to ask for a solution (or opinion) to.
Consider I have a human body; this human body is light by default and therefore, it's arms are also light. My pseudo-code in CSS may look like the below:
.human {
background-color: white;
}
.human__arm {
background-color: white;
}
Now we want to add a class for humans who are dark. We can create a modifier for this:
.human--dark {
background-color: black;
}
The problem I am facing is that by now, the human's arm is still white. We can make them black in two ways that I know of:
Solution A
.human--dark {
background-color: black;
}
.human--dark .human__arm {
background-color: black;
}
This solution breaks the BEM methodology by adding specificity to the CSS. However, I feel that this solution is more portable where you are sure to only modify the human and assume that all of its elements will also adapt to the changes of the parent.
Solution B
.human--dark {
background-color: black;
}
.human__arm--dark {
background-color: black;
}
I like to think that a 'Block' is a reusable component in BEM. If the human has various other body parts that also need turning white, it seems less maintainable to modify all of the blocks elements in order to achieve this.
While background-color: inherit; may look like a solution to this case, in a real-world application we may have a dark background that contains elements that require light text.
How would we modify the light text to become dark when its parent block becomes light?
The first solution is the better one assuming that a dark human may not necessarily have a white arm.
The idea behind BEM syntax is to allow for composability. Writing your selector that way defeats this purpose.
A better way to define these selectors is:
.human {} /* block */
.human--dark {} /* modified block */
.human--arm {} /* block element */
These can be altogether composed this way in markup:
<div class="human human--dark">
<div class="human__arm">
Human
</div>
</div>
For your second question, you may want to take advantage of a CSS preprocessor to compute the inverse of the background color for the text color.
In Sass, it's done this way using a custom mixin:
#mixin duotone ($color) {
background-color: $color;
color: invert($color);
}
.human {
#include duotone(white);
}
.human--dark {
#include duotone(black);
}
.human__arm {
}
In order to modify child elements via parent modifier
we should nest the element selector like below:
Block with an element:
.human {
background-color: white;
}
.human__arm {
background-color: white;
}
Block Modifier modifying the child element:
.human--dark {
background-color: black;
}
.human--dark .human__arm {
background-color: black;
}
If we want to achieve the same in SCSS, we can use the following approach:
.human {
background-color: white;
&__arm {
background-color: white;
}
&--dark { // block modifier
background-color: black;
.human { // block
&__arm {
background-color: black;
}
}
}
}
If you're using scss you can use interpolation to avoid duplication
.human {
$c: &;
background-color: white;
&__arm {
background-color: white;
}
&--dark {
background-color: black;
#{$c}__arm {
background-color: black;
}
}
}
Also, this may not be relevant to the question, but using background-color: inherit on the arms would mean you wouldn't have to change any css for the arms as it would inherit from the parent.
(Posts such as MVC #import html keyword show similar problems to mine, but the solution does not seem to fix my problem.)
I am trying to use the below code within a .cshtml file. The css #import conflicts with Razor, so I tried ##import but to no avail. I get runtime errors in Visual studio such as "The controller for path '/media/css/site_jui.ccss' could not be found."
<style type="text/css" media="screen">
#import "/media/css/site_jui.ccss";
#import "/release-datatables/media/css/demo_table_jui.css";
#import "/media/css/jui_themes/smoothness/jquery-ui-1.7.2.custom.css";
/*
* Override styles needed due to the mix of three different CSS sources! For proper examples
* please see the themes example in the 'Examples' section of this site
*/
.dataTables_info { padding-top: 0; }
.dataTables_paginate { padding-top: 0; }
.css_right { float: right; }
#example_wrapper .fg-toolbar { font-size: 0.8em }
#theme_links span { float: left; padding: 2px 10px; }
</style>
You can use double # to escape the #:
##import "/media/css/site_jui.css";
This will work:
#string.Format("#")import "/media/css/site_jui.css";
Are there any useful techniques for reducing the repetition of constants in a CSS file?
(For example, a bunch of different selectors which should all apply the same colour, or the same font size)?
Recently, variables have been added to the official CSS specs.
Variables allow you to so something like this :
body, html {
margin: 0;
height: 100%;
}
.theme-default {
--page-background-color: #cec;
--page-color: #333;
--button-border-width: 1px;
--button-border-color: #333;
--button-background-color: #f55;
--button-color: #fff;
--gutter-width: 1em;
float: left;
height: 100%;
width: 100%;
background-color: var(--page-background-color);
color: var(--page-color);
}
button {
background-color: var(--button-background-color);
color: var(--button-color);
border-color: var(--button-border-color);
border-width: var(--button-border-width);
}
.pad-box {
padding: var(--gutter-width);
}
<div class="theme-default">
<div class="pad-box">
<p>
This is a test
</p>
<button>
Themed button
</button>
</div>
</div>
Unfortunately, browser support is still very poor. According to CanIUse, the only browsers that support this feature today (march 9th, 2016), are Firefox 43+, Chrome 49+, Safari 9.1+ and iOS Safari 9.3+ :
Alternatives :
Until CSS variables are widely supported, you could consider using a CSS pre-processor language like Less or Sass.
CSS pre-processors wouldn't just allow you to use variables, but pretty much allow you to do anything you can do with a programming language.
For example, in Sass, you could create a function like this :
#function exponent($base, $exponent) {
$value: $base;
#if $exponent > 1 {
#for $i from 2 through $exponent {
$value: $value * $base;
}
}
#if $exponent < 1 {
#for $i from 0 through -$exponent {
$value: $value / $base;
}
}
#return $value;
}
Elements can belong to more than one class, so you can do something like this:
.DefaultBackColor
{
background-color: #123456;
}
.SomeOtherStyle
{
//other stuff here
}
.DefaultForeColor
{
color:#654321;
}
And then in the content portion somewhere:
<div class="DefaultBackColor SomeOtherStyle DefaultForeColor">Your content</div>
The weaknesses here are that it gets pretty wordy in the body and you're unlikely to be able to get it down to listing a color only once. But you might be able to do it only two or three times and you can group those colors together, perhaps in their own sheet. Now when you want to change the color scheme they're all together and the change is pretty simple.
But, yeah, my biggest complain with CSS is the inability to define your own constants.
You should comma seperate each id or class for example:
h1,h2 {
color: #fff;
}
You can use global variables to avoid duplicacy.
p{
background-color: #ccc;
}
h1{
background-color: #ccc;
}
Here, you can initialize a global variable in :root pseudo class selector. :root is top level of the DOM.
:root{
--main--color: #ccc;
}
p{
background-color: var(--main-color);
}
h1{
background-color: var(--main-color);
}
NOTE: This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for the proper prefixes to use in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the spec changes. More Info here
However, you can always use the Syntactically Awesome Style Sheets i.e.
In case Sass, you have to use $variable_name at the top to initialize the global variable.
$base : #ccc;
p{
background-color: $base;
}
h1{
background-color: $base;
}
You can use dynamic css frameworks like less.
Personally, I just use comma-separed selector, but there some solution for writing css programmatically. Maybe this is a little overkill for you simpler needs, but take a look at CleverCSS (Python)
Try Global variables to avoid duplicate coding
h1 {
color: red;
}
p {
font-weight: bold;
}
Or you can create different classes
.deflt-color {
color: green;
}
.dflt-nrml-font {
font-size: 12px;
}
.dflt-header-font {
font-size: 18px;
}
As far as I know, without programmatically generating the CSS file, there's no way to, say, define your favorite shade of blue (#E0EAF1) in one and only one spot.
You could pretty easily write a computer program to generate the file. Execute a simple find-and-replace operation and then save as a .css file.
Go from this source.css…
h1,h2 {
color: %%YOURFAVORITECOLOR%%;
}
div.something {
border-color: %%YOURFAVORITECOLOR%%;
}
to this target.css…
h1,h2 {
color: #E0EAF1;
}
div.something {
border-color: #E0EAF1;
}
with code like this… (VB.NET)
Dim CssText As String = System.IO.File.ReadAllText("C:\source.css")
CssText = CssText.Replace("%%YOURFAVORITECOLOR%%", "#E0EAF1")
System.IO.File.WriteAllText("C:\target.css", CssText)
You can use multiple inheritance in your html elements (e.g. <div class="one two">) but I'm not aware of a way of having constants in the CSS files themselves.
This link (the first found when googling your question) seems to have a fairly indepth look at the issue:
http://icant.co.uk/articles/cssconstants/
CSS Variables, if it ever becomes implemented in all major browsers, may one day resolve this issue.
Until then, you'll either have to copy and paste, or use a preprocessor of whatever sort, like others have suggested (typically using server-sider scripting).
:root {
--primary-color: red;
}
p {
color: var(--primary-color);
}
<p> some red text </p>
You can change color by JS
var styles = getComputedStyle(document.documentElement);
var value = String(styles.getPropertyValue('--primary-color')).trim();
document.documentElement.style.setProperty('--primary-color', 'blue');