From now on, all we need to do to create an instance with a different color scheme is to create a new class.

// HTML 

// CSS.icon-colors-alt { --color-1: brown; --color-2: yellow; --color-3: pink;}

If you still want to have monochrome icons, you don’t have to repeat the same color on every CSS variable. Instead, you can declare a single fill rule: because CSS variables aren’t defined, it will fall back on your fill declaration.

.icon-monochrome { fill: grey;}

Your fill declaration will work because the fill attributes on the original SVG are set with undefined CSS variables values.

What to name my CSS variables?

There are usually two routes you can take when it comes to naming things in CSS: descriptive or semantic. Descriptive means calling a color what it is: if you’re storing #ff0000, you’d call it --red. Semantic means calling the color by how it’s applied: if you’re using #ff0000 for the handle of a coffee cup, you’d call it --cup-handle-color.

Descriptive names might be your first instinct. It feels DRYer since #ff0000 can be used for other things than the handle of the coffee cup. A --red CSS variable is reusable for other icon paths that need to be red. After all, this is how utility-first CSS works and it’s a fine system.

Problem is, in our case we can’t apply granular classes to the elements we want to style. Utility-first principles can’t apply, because we have a single reference for each icon, and we have to style it through class variations.

Using semantic class names, like --cup-handle-color for example, makes more sense for this use case. When you want to change the color of a part of an icon, you instantly know what it is and what to override. The class name will remain relevant no matter what color you assign.

To default or not to default

It’s tempting to make the multi-colored version of your icons their default state. This way, you could use them with no need for extra styling, and you would add your own classes only when necessary.

There are two ways to achieve that: :root and var() default.

:root

You can define all your CSS variables on the :root selector. This keeps them all in one place and allows you to “share” similar colors. :root has the lowest priority, so it remains easy to override.

:root { --color-1: red; --color-2: green; --color-3: blue; --color-4: var(--color-1);}

.icon-colors-alt { --color-1: brown; --color-2: yellow; --color-3: pink; --color-4: orange;}

However, there are major drawbacks to this method. First, keeping color definitions separate from their respective icons can be confusing. When you decide to override them, you have to go back and forth between the class and the :root selector. But more importantly, it doesn’t allow you to scope your CSS variables, thus keeps you from reusing the same names.

Most of the time, when an icon only uses one color, I use the --fill-color name. It’s simple, understandable, and it makes sense to use the same name for all icons that only need one fill color. If I have to declare all variables in the :root declaration, I can’t have several --fill-color. I’ll be forced to define --fill-color-1, --fill-color-2, or use namespaces like --star-fill-color, --cup-fill-color.

var() default

The var() function, which you use to assign a CSS variable to a property, can take a default value as a second argument.

  my-first-icon    

Until you define --color-1, --color-2 and --color-3, the icon will use the default values you set for each th>. This solves the global scope issue we have when using :root, but be careful: you now have a default value and it’s doing its job. As a result, you can’t use a single fill declaration to define monochrome icons anymore. You’ll have to assign the color to every CSS variable used on the icon, one by one.

Setting default values can be useful, but it’s a tradeoff. I suggest you don’t make it a habit, and only do it when it makes sense for a given project.

How browser-friendly is all that?

CSS variables are compatible with most modern browsers, but as you probably expect it, Internet Explorer doesn’t support it at all. Not even IE11, and since development was discontinued in favor of Edge, there’s no chance it will ever get up to speed.

Now, just because a feature isn’t supported by a browser you need to cater to, that doesn’t mean you have to rule it out altogether. In such cases, go for graceful degradation: offer multi-colored icons to modern browsers, and provide a fallback fill color for older ones.

What you want to do is set a declaration that will only work if CSS variables aren’t supported. This can be achieved by setting the fill property to the fallback color: if CSS variables are supported, it won’t even be taken into account. If they’re not, your fill declaration will apply.

If you’re using Sass, this can be abstracted into a @mixin.

@mixin icon-colors($fallback: black) { fill: $fallback; @content;}

We can now define color schemes without worrying about browser compatibility.

.cup { @include icon-colors() { --cup-color: red; --smoke-color: grey; };}

.cup-alt { @include icon-colors(green) { --cup-color: green; --smoke-color: grey; };}

Passing the CSS variables in the mixin through @content is optional. If you do it outside, the compiled CSS will be the same. But it can be helpful to package it all in one place: you can fold snippets in your editor and visually identify declarations that go together.

Check out this pen on different browsers. On up-to-date versions of Firefox, Chrome, and Safari, the last two cups will respectively be red with grey smoke and blue with grey smoke. On Internet Explorer and Edge before version 15, the third cup will be all red and the fourth will be all blue! ✨

If you want to learn more about SVG symbol icons (and SVG in general), I strongly suggest you read everything by Sara Soueidan. And if you have any question about CSS symbol icons, don’t hesitate to hit me up on Twitter!

Originally published at frontstuff.io.