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Like other CSS properties, when we define a CSS variable, we are also giving that variable a set scope. In CSS, the scope is what determines where a variable will work based on where it is declared. Variables can have two kinds of scope: local and global. So far we have only dealt with variables with local scope.

A locally scoped CSS variable will only affect the specific HTML element that it is declared in along with any children that element may contain.

<nav id="menu-items"> <ul> <li><a href='#'>One</a></li> <li><a href='#'>Two</a></li> <li><a href='#'>Three</a></li> </ul> </nav>

For instance, in the above code snippet, the <nav> element with the id of 'menu-items' contains an unordered list.

#menu-items { --menu-color-blue: blue; } #menu-items a { color: var(--menu-color-blue); }

Because the --menu-color-blue variable was declared inside the #menu-items selector, only #menu-items and its children can reference the variable.

Globally scoped variables are declared in the :root pseudo-class. This pseudo-class points to the root element of the document, hence its name. In most cases that root element is actually the <html> element. By declaring variables in :root they can be applied globally across the entire HTML document.

If we were to modify the previous example to instead declare --menu-color-blue inside of :root, then that variable would be able to be referenced anywhere in the document.

:root { --menu-color-blue: blue; } #menu-items a { color: var(--menu-color-blue); }

It is common practice to define variables inside the :root selector but not mandatory. There are plenty of good reasons for declaring variables with limited scope. For instance, if a large website is being designed then it could be a cleaner solution to create variables within relevant components instead of having all the variables pile up in :root.

Instructions

1.

We want to alternate background colors for each artist that has a new release. Right above the .container selector ruleset add an empty :root pseudo-class.

2.

Inside the :root pseudo-class create a variable called --group-one-background-color that has a value of #a01c32.

3.

Still inside of the :root pseudo-class create a variable called --group-two-background-color that has a value of #8A978A.

4.

Set the --group-one-background-color variable as the value of the background property for the .artist selector ruleset and set --group-two-background-color as the background property for .artist:nth-child(even).

5.

Inside the .btn selector, create a variable called --button-hover-color and set its value to be #7271D8.

6.

Finally, inside of the .btn:hover, .btn:focus selector ruleset create a background property and set its value to be --button-hover-color.

Note that if you try to use this variable outside of the .btn selector ruleset, nothing will happen!

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