Using CSS @Variables

Using CSS @Variables

I would use a CSS preprocessor such as Sass or Less.

How to use CSS variables with Tailwind CSS

Assuming you have already added TailwindCSS to your project and that your CSS file is called global.css.

First, you need to edit global.css to look like this:

@tailwind base;
@tailwind components;
@tailwind utilities;

.root,
#root,
#docs-root {
  --primary-color: #fff;
  --secondary-color: #000;
}

And then, in order to be able to use them, you need to update tailwind.config.js with the new CSS variables like so:

module.exports = {
  theme: {
    extend: {
      colors: {
        "primary-color": "var(--primary-color)",
        "secondary-color": "var(--secondary-color)"
      },
    },
  },
};

You can now use these variables as desired:

<div class="bg-primary-color">
  <h1>Hello World</h1>
</div>

Creating CSS Global Variables : Stylesheet theme management

Latest Update: 16/01/2020

CSS Custom Properties (Variables) have arrived!

It's 2020 and time to officially roll out this feature in your new applications.

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Preprocessor "NOT" required!

There is a lot of repetition in CSS. A single color may be used in several places.

For some CSS declarations, it is possible to declare this higher in the cascade and let CSS inheritance solve this problem naturally.

For non-trivial projects, this is not always possible. By declaring a variable on the :root pseudo-element, a CSS author can halt some instances of repetition by using the variable.

How it works

Set your variable at the top of your stylesheet:

CSS

Create a root class:

:root {
}

Create variables (-- [String] : [value])

:root {
  --red: #b00;
  --blue: #00b;
  --fullwidth: 100%;
}

Set your variables anywhere in your CSS document:

h1 {
  color: var(--red);
}
#MyText {
  color: var(--blue);
  width: var(--fullwidth);
}

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BROWSER SUPPORT / COMPATIBILITY

See caniuse.com for current compatability.

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Firefox: Version 31+ (Enabled by default)

Supported since 2014 (Leading the way as usual.)

More info from Mozilla

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Chrome: Version 49+ (Enabled by default).

Supported since 2016

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Safari/IOS Safari: Version 9.1/9.3 (Enabled by default).

Supported since 2016

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Opera: Version 39+ (Enabled by default).

Supported since 2016

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Android: Version 52+ (Enabled by default).

Supported since 2016

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Edge: Version 15+ (Enabled by default).

Supported since 2017

CSS Custom Properties landed in Windows Insider Preview build 14986

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IE: When pigs fly.

It's time to finally let this ship sink. No one enjoyed riding her anyway. ☺

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W3C SPEC

Full specification for upcoming CSS variables

Read more

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TRY IT OUT

A fiddle and snippet are attached below for testing:

(It will only work with supported browsers.)

DEMO FIDDLE

:root {
  --red: #b00;
  --blue: #4679bd;
  --grey: #ddd;
  --W200: 200px;
  --Lft: left;
}
.Bx1,
.Bx2,
.Bx3,
.Bx4 {
  float: var(--Lft);
  width: var(--W200);
  height: var(--W200);
  margin: 10px;
  padding: 10px;
  border: 1px solid var(--red);
}
.Bx1 {
  color: var(--red);
  background: var(--grey);
}
.Bx2 {
  color: var(--grey);
  background: black;
}
.Bx3 {
  color: var(--grey);
  background: var(--blue);
}
.Bx4 {
  color: var(--grey);
  background: var(--red);
}

<p>If you see four square boxes then variables are working as expected.</p>

<div class="Bx1">I should be red text on grey background.</div>
<div class="Bx2">I should be grey text on black background.</div>
<div class="Bx3">I should be grey text on blue background.</div>
<div class="Bx4">I should be grey text on red background.</div>

Parse Javascript variable to CSS variables

I think you're looking for something similar to this:

var parentElement = document.documentElement || document.body;
parentElement.style.maxWidth = parentElement.clientWidth + 'px';
parentElement.style.maxHeight = parentElement.clientHeight + 'px';

How to apply the styles for one variable

If you want to set CSS style for text-box(HTML - input type - text) using java script

Try this

<script type="text/javascript">
    function changeStyle() {
       var cssString = "css style";
       document.getElementById("my_Element_id").style.cssText = cssString;
    }
</script>

<input type="text" id="my_Element_id" />
<input type="button" value="Change" onlclick="changeStyle()" />

Replace css style to your actual style.

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