CSS Variables for Theming

1. Introduction

In component-driven development, creating a consistent theming system is essential for maintaining a cohesive UI. CSS Variables (also known as Custom Properties) provide a powerful way to implement theming across your components.

2. What are CSS Variables?

CSS Variables are entities defined by CSS authors that contain specific values to be reused throughout a document. They are defined using the --variable-name syntax and can be accessed using the var(--variable-name) function.

:root {
    --primary-color: #3498db;
    --secondary-color: #2ecc71;
    --font-size: 16px;
}
            

3. Theming with CSS Variables

CSS Variables allow for dynamic theming by changing values at runtime. This means you can create themes by simply altering the variables without modifying your CSS selectors directly.

Step-by-Step Example

1. Define CSS Variables in the :root selector.
2. Apply these variables in your CSS rules.
3. Change the variable values to switch themes.

Applying CSS Variables

.button {
    background-color: var(--primary-color);
    color: white;
    font-size: var(--font-size);
}

.button-secondary {
    background-color: var(--secondary-color);
}
        

Changing Theme Dynamically

function changeTheme(newTheme) {
    document.documentElement.style.setProperty('--primary-color', newTheme.primary);
    document.documentElement.style.setProperty('--secondary-color', newTheme.secondary);
}
        

4. Best Practices

• Use descriptive variable names.
• Group related variables together for easier maintenance.
• Fallback values are a good practice to ensure compatibility.
• Document your variables for clarity.

5. FAQ