CSS Custom Properties (Variables)

The var() function can be used to insert the value of a custom property.

The var() Function

Variables in CSS should be declared within a CSS selector that defines its scope. For a global scope you can use either the :root or the body selector.

The variable name must begin with two dashes (--) and is case sensitive!

The syntax of the var() function is as follows:

var(custom-name, value)

Example -

<!DOCTYPE html>
<html>
<head>
<style>
:root {
  --main-bg-color: coral;
  --main-txt-color: blue;  
  --main-padding: 15px;  
}

#div1 {
  background-color: var(--main-bg-color);
  color: var(--main-txt-color);  
  padding: var(--main-padding);
}

#div2 {
  background-color: var(--main-bg-color);
  color: var(--main-txt-color);
  padding: var(--main-padding);
}

#div3 {
  background-color: var(--main-bg-color);
  color: var(--main-txt-color);
  padding: var(--main-padding);
}
</style>
</head>
<body>

<h1>The var() Function</h1>

<div id="div1">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam semper diam at erat pulvinar, at pulvinar felis blandit.</div>
<br>

<div id="div2">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam semper diam at erat pulvinar, at pulvinar felis blandit.</div>
<br>

<div id="div3">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam semper diam at erat pulvinar, at pulvinar felis blandit.</div>

<p><strong>Note:</strong> Internet Explorer and Edge 14 and earlier versions do not support the var() function.</p>

</body>
</html>