I'm currently working on an online code editor. (like jsfiddle codepen etc...)
I got everything working, but I ran into one problem; If a user does something like this:
button {
background-color: red;
}
It also changes the properties of my "run code" and "reset" button I made.
same thing with other things like a div;
div {
padding: 500em;
}
because this will also change the div's Im using in my own code.
I fixed the issue using !importand tags after every line in my css but I'm wordering if there is any other way to fix this? or is !importand really the only way.
As said in the comment by CBroe. To do this you can use iframe.
A more original solution would be to create a web component with a shadow root (which isolate the style too). The support for this is not too bad even if it's fairly new :
But, I've used it myself and it's a little bit harder to understand at first
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.
I have made a complete Bootstrap grid system. I am now uploading my code to a CMS system, and can see there is some CSS from the backend, there is messing up my grid.
If I untick the following code in the inspector window, everything is looking perfect. When the following code is ticked in the inspector window everything is messed up. Is it possible to overwrite this code somehow, so the class is not used?
.cms-area img {
width: 100%;
}
You can use !important in such cases but use it sparingly. Best is to remove the unwanted code and not use !important. !important might cause issues later that are difficult to debug. If possible include your css after other css is included in the code. In CSS, rules that appear later take precedence over earlier rules
Edit:
Set width to auto instead of 100% to fix your alignment issue
Below given is the ideal way to manage css since it allows you to attribute your style content and lets you override the style already applied elsewhere.
.cms-area .your-class img {
width: <your choice>;
}
Today I was trying to create a dummy css rule for testing and investigation.
.dummy {
some-style : somevalue;
}
Ideally the class should have no visible effect. I want to be able to apply the class to elements but cause the least visible effect possible on any elements it is applied to. For example
<div class="dummy"> should look and behaves as much as possible like <div>
I did not want the class to be empty. Can anyone suggest a style that I could add to the class that would have the least visible impact when applied to a general html element? I can't think of anything completely harmless.
UPDATE: I wanted to add the style to some existing html. The reason was to use the style as a marker for diagnostic purposes. It would help me see when and where styles and stylesheets were getting loaded/cached and where and why some styles were getting overridden, sometimes by the browser defaults which seemed odd. At the time I didn't have exclusive use of the system I was working on so I wanted something that was going to be invisible to other users but I could see in Developer Tools.
UPDATE 2 : the html/css wasn't written by me and I didn't have my own environment in which to work. I was trying to investigate some problems in-situ in someone else's system. I had tried using DevTools in the browser but wasn't getting anywhere with that. I wanted to be able to make some small changes to their html/css to aid my diagnostics. I didn't want them to have any obvious effect on the system for other people (except in DevTools, viewed by me).
It was a Wordpress site and they only had two environments, one for live and one for testing. I was working with the test system. There were other people testing at the time, though mainly checking content.
The real thorny problem was why was the font-size in the calendar widget much larger than everything else on the site? Inspecting using DevTools I could see the font-size style was getting overridden by the browser default style when it seemed to me there were other css selectors that should have taken precedence. It looked bizarre. In the end it turned out to be a missing !DOCTYPE tag in the html. So nothing to do with the css itself.
I didn't like this way of working, fiddling in someone's system, but there wasn't much else to do and it did help to resolve the problem for them.
Hopefully I don't have to do this again, but ever since I have been wondering what was the most harmless style that I could have used?
I thought I would ask here as there must be people who know CSS better than me.
You can use this:
.dummy{
min-width: 0;
min-height: 0;
}
If you just need anything beeing set you could assign rules that are default anyway. For block elements like div set
.block-class { display: block; }
And for inline elements like span
.inline-class { display: inline; }
Of course it could be an issue doing so in some rare cases but in general it's quite harmless I guess.
In principle, for any property you can have an arrangement like this:
div {
some-style : a-valid-value-for-some-style;
}
.dummy {
some-style : a-different-valid-value-for-some-style;
}
And .dummy's style will have an effect, no matter what some-style is.
Your best bet is to make use of CSS variables. These are custom properties and start with a double hyphen. so
.dummy {
--dummy-style: foo;
}
will make --dummy-style a property with value "foo". So long as you don't employ the variable as the value in another property, it will have no visible effect.
I am using LESS CSS for WordPress Theme development. I have just noticed that when I compile the LESS files to CSS all of the comments placed inside LESS file are added to the top of the CSS file (and not on the right line)... is there any way to avoid this? I am using Less for mac as a compiler also tried the simpLess but the same problem occurs.
Whilst not ideal, and certainly against convention, I place my comments inside the style definition.
eg:
.style {
/* Comment for .style */
...style definition...
.inner-style {
/* Comment for .inner-style */
...style definition...
}
}