I'm trying to achieve something similar like here: How to override css prefers-color-scheme setting, with the difference that I'm using SCSS.
There are some top-level variables defined:
$content-primary: #000000;
$content-secondary: #FFFFFF;
I want to overwrite those values, depending on the information on the client (localStorage, media query). I started by setting the data-attribute to the html element, e.g. document.documentElement.setAttribute("data-theme", "dark");.
// Some SCSS magic here checking data attributes
// When data-theme="dark" is set, the following should be applied:
$content-primary: #F1F1F1;
$content-secondary: #222222;
I've tried to use the same logic as in the related question, but that does not work.
[data-theme="dark"] {
$content-primary: #F1F1F1;
$content-secondary: #222222;
}
Is this somehow possible?
I have done theming on a project and used !default
Click here to read documentation
But seeing what you want to do, I suggest you to use native CSS var(--content-primary)
This Basic CSS variables can be overwritten not only based on attribute/class/parent etc. But also based on Media Query which makes them an incredible versatile tool.
I have a Wordpress website which contains a lot of pre-written CSS-code. One of the prewritten code-snippets looks like this:
input[type=url] {
color: #666666;
... (a lot of other styling properties)
}
Now I wanted to create a design for a single page which contains an input field of type url.
<input type="url" id="input_url" class="dtd-settings-element"></input>
The problem is, that I want to style this input field completely on my own but the pre-written code is affecting that style. Is there a possibility to "deactivate" the pre-written CSS snippet for my new input field?
I know that I can overwrite all the attributes from the pre-written snippet in my dtd-settings-element class. But doing this for multiple elements would not be optimal.
Thanks in advance for pointing me in the right direction :)
EDIT:
Last thing I tried was:
input[type=url]:not(#input_url)
You can use the unique id of the input field with !important to target that element and just apply whatever style you want...
#input_url {
color: red !important;
}
You can try to override styling.
#input_url input[type=url] {
color: #000;
font-size: initial;
...
}
Unfortunately there is no way to deactivate pre-written CSS in your terms. All the possibilities you have already mentioned:
Override all class properties
Modify original styles
Change type attribute
However you can change tag from input to (for example) textarea.
Is there any way to use conditional statements in CSS?
I'd say the closest thing to "IF" in CSS are media queries, such as those you can use for responsive design. With media queries, you're saying things like, "If the screen is between 440px and 660px wide, do this". Read more about media queries here: http://www.w3schools.com/cssref/css3_pr_mediaquery.asp, and here's an example of how they look:
#media screen and (max-width: 300px) {
body {
background-color: lightblue;
}
}
That's pretty much the extent of "IF" within CSS, except to move over to SASS/SCSS (as mentioned above).
I think your best bet is to change your classes / IDs within the scripting language, and then treat each of the class/ID options in your CSS. For instance, in PHP, it might be something like:
<?php
if( A > B ){
echo '<div class="option-a">';
}
else{
echo '<div class="option-b">';
}
?>
Then your CSS can be like
.option-a {
background-color:red;
}
.option-b {
background-color:blue;
}
No. But can you give an example what you have in mind? What condition do you want to check?
Maybe Sass or Compass are interesting for you.
Quote from Sass:
Sass makes CSS fun again. Sass is CSS, plus nested rules, variables, mixins, and more, all in a concise, readable syntax.
CSS itself doesn't have conditional statements, but here's a hack involving custom properties (a.k.a. "css variables").
In this trivial example, you want to apply a padding based on a certain condition—like an "if" statement.
:root { --is-big: 0; }
.is-big { --is-big: 1; }
.block {
padding: calc(
4rem * var(--is-big) +
1rem * (1 - var(--is-big))
);
}
So any .block that's an .is-big or that's a descendant of one will have a padding of 4rem, while all other blocks will only have 1rem. Now I call this a "trivial" example because it can be done without the hack.
.block {
padding: 1rem;
}
.is-big .block,
.block.is-big {
padding: 4rem;
}
But I will leave its applications to your imagination.
The #supports rule (92% browser support July 2017) rule can be used for conditional logic on css properties:
#supports (display: -webkit-box) {
.for_older_webkit_browser { display: -webkit-box }
}
#supports not (display: -webkit-box) {
.newer_browsers { display: flex }
}
The only conditions available in CSS are selectors and #media. Some browsers support some of the CSS 3 selectors and media queries.
You can modify an element with JavaScript to change if it matches a selector or not (e.g. by adding a new class).
I would argue that you can use if statements in CSS. Although they aren't worded as such. In the example below, I've said that if the check-box is checked I want the background changed to white. If you want to see a working example check out www.armstrongdes.com. I built this for a client. Re size your window so that the mobile navigation takes over and click the nav button. All CSS. I think it's safe to say this concept could be used for many things.
#sidebartoggler:checked + .page-wrap .hamb {
background: #fff;
}
// example set as if statement sudo code.
if (sidebaretoggler is checked == true) {
set the background color of .hamb to white;
}
CSS has become a very powerful tool over the years and it has hacks for a lot of things javaScript can do
There is a hack in CSS for using conditional statements/logic.
It involves using the symbol '~'
Let me further illustrate with an example.
Let's say you want a background to slide into the page when a button is clicked. All you need to do is use a radio checkbox.
Style the label for the radio underneath the button so that when the button is pressed the checkbox is also pressed.
Then you use the code below
.checkbox:checked ~ .background{
opacity:1
width: 100%
}
This code simply states IF the checkbox is CHECKED then open up the background ELSE leave it as it is.
css files do not support conditional statements.
If you want something to look one of two ways, depending on some condition, give it a suitable class using your server side scripting language or javascript. eg
<div class="oh-yes"></div>
<div class="hell-no"></div>
There is no native IF/ELSE for CSS available. CSS preprocessors like SASS (and Compass) can help, but if you’re looking for more feature-specific if/else conditions you should give Modernizr a try. It does feature-detection and then adds classes to the HTML element to indicate which CSS3 & HTML5 features the browser supports and doesn’t support. You can then write very if/else-like CSS right in your CSS without any preprocessing, like this:
.geolocation #someElem {
/* only apply this if the browser supports Geolocation */
}
.no-geolocation #someElem {
/* only apply this if the browser DOES NOT support Geolocation */
}
Keep in mind that you should always progressively enhance, so rather than the above example (which illustrates the point better), you should write something more like this:
#someElem {
/* default styles, suitable for both Geolocation support and lack thereof */
}
.geolocation #someElem {
/* only properties as needed to overwrite the default styling */
}
Note that Modernizr does rely on JavaScript, so if JS is disabled you wouldn’t get anything. Hence the progressive enhancement approach of #someElem first, as a no-js foundation.
Changing your css file to a scss file would allow you to do the trick. An example in Angular would be to use an ngClass and your scss would look like:
.sidebar {
height: 100%;
width: 60px;
&.is-open {
width: 150px
}
}
While this feels like a bit of a hack, and may not work perfectly in all browsers, a method I have used recently combines the fact that CSS (at least in Chrome) seems to ignore invalid values set on properties, and we can set custom properties that fall back to their default value when invalid.
(Note: I haven't deeply tested this, so treat it as a hacky proof of concept/possible idea)
The following is written in SCSS, but it should work just as well in standard CSS:
.hero-image {
// CSS ignores invalid property values
// When this var is set to an image URL, the browser will ignore it
// When this var isn't set, then we will use the default fallback for the var, which is 'none'
display: var(--loading-page-background-image, none);
// This part isn't directly relevant to my 'if' example, but shows how I was actually using this custom property normally
background-image: var(--loading-page-background-image, none);
}
I'm setting the custom property from JavaScript / React, but it would likely work regardless of how you set it:
// 'true' case
const chosenLoaderUrl = "https://www.example.com/loader.png";
// 'false' case
//const chosenLoaderUrl = "";
// containerRef is just a reference to the div object, you could get this with
// jquery or however you need. Since I'm in React, I used useRef() and attached
// that to my div
containerRef.current.style.setProperty(
"--loading-page-background-image",
`url(${chosenLoaderUrl})`
);
When chosenLoaderUrl is set to my url, that url is an invalid value for the display property, so it seems to get ignored.
When chosenLoaderUrl is set to an empty value, it falls back to the default value in my var() statement, so sets display to none
I'm not sure how 'generalisable' this concept it, but figured I would add it to the other suggestions here in case it is useful to anyone.
Your stylesheet should be thought of as a static table of available variables that your html document can call on based on what you need to display. The logic should be in your javascript and html, use javascript to dynamically apply attributes based on conditions if you really need to. Stylesheets are not the place for logic.
You can use combination of jquery and css classes i.e. I want to change a font color of certain element depending on the color of the background:
CSS:
.h3DarkMode{
color: lightgray;
}
.h3LightMode{
color: gray;
}
HTML:
<h3 class="myText">My Text Here...</h3>
JQuery:
var toggleMode = localStorage.getItem("toggleMode");
if (toggleMode == "dark"){
$(".myText").removeClass("h3LightMode").addClass("h3DarkMode");
}else{
$(".myText").removeClass("h3DarkMode").addClass("h3LightMode");
}
No you can't do if in CSS, but you can choose which style sheet you will use
Here is an example :
<!--[if IE 6]>
Special instructions for IE 6 here
<![endif]-->
will use only for IE 6 here is the website where it is from http://www.quirksmode.org/css/condcom.html , only IE has conditional comments. Other browser do not, although there are some properties you can use for Firefox starting with -moz or for safari starting with -webkit. You can use javascript to detect which browser you're using and use javascript if for whatever actions you want to perform but that is a bad idea, since it can be disabled.
Is it possible to change the root color palette of a browser on a certain page?
For example.
<div style="color:blue">Blue Text</>
color: blue => color:#0000FF (browser assume)
I want to tell the browser that "blue" is #0000BB. (either through stylesheet.css or javascript modifying its default palletes )
Plus, is it possible to add more standard color to the pallete?
Like: navyblue => #3e3e80
I'm not sure if it's possible to overwrite the root colour palette itself, but what you can do is make use of custom CSS properties to achieve almost the same thing.
Simply define the colours that you want in the :root, using -- as a prefix. You can then reference these colours by using var(--variable) as the color value.
This can be seen in the following:
:root {
--blue: #0000FF;
--navyblue: #3e3e80;
}
div {
color: var(--blue);
}
span {
color: var(--navyblue);
}
<div>Blue</div>
<span>Navy Blue</span>
Using CSS variables in this way allows you to easily change a colour throughout the entire site by only changing one line of code, and also allows for additional colours to be easily mapped out.
I use the same 3-4 colors on 99% of the elements on my website. I know of absolutely no way this is possible, but I'd thought I would ask.
Is there any way to specify a color and quickly reference it within other elements further down the page? For example:
.red_color {
color: #FF0000;
}
Now, further down the page we have other elements:
div.example {
padding: 10px;
color: [REFERENCE ABOVE]
}
This way, if the color ever changes, I can update it in one place and all the other elements will follow suit.
I know it is possible if I list all the elements in one place, like:
div.example, div.other_example, p {
color: #FF0000;
}
But this way, every time I add another element to the stylesheet, I have to remember to add it to this list.
Any other ways of doing this?
Thanks.
Yes, but not in CSS. Look at using LESS or SASS. Then you can define variables and use them as you're suggesting.