CSS variables, officially known as CSS custom properties, have transformed how we write and maintain CSS. In this post, we'll explore how to effectively use CSS variables to create more maintainable, theme-able designs.

What Are CSS Variables?

CSS variables allow you to define specific values that can be reused throughout your stylesheet. Unlike preprocessor variables (like those in Sass or Less), CSS variables are part of the DOM and can be updated using JavaScript.

Here's a basic example:

:root {
  --main-color: #3b82f6;
  --text-color: #333333;
}

.header {
  background-color: var(--main-color);
  color: var(--text-color);
}

Benefits of Using CSS Variables

There are several advantages to using CSS variables:

  1. Centralized values: You can define colors, spacing, and other values in one place
  2. Dynamic updates: Variables can be changed with JavaScript
  3. Contextual variations: You can redefine variables within specific selectors
  4. Reduced redundancy: No need to repeat the same values throughout your CSS

Creating a Theme System

One of the most powerful applications of CSS variables is creating theme systems. By changing a few variables, you can completely transform the look of your site:

/* Light theme (default) */
:root {
  --bg-color: #ffffff;
  --text-color: #333333;
}

/* Dark theme */
.dark-theme {
  --bg-color: #1f2937;
  --text-color: #f3f4f6;
}

Stay tuned for more advanced CSS techniques in future posts!