Unlocking REM CSS: Improving Websites

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What is REM in CSS?

Scaling Websites for Optimal User Experience

In the world of web development, creating a website that looks good and functions flawlessly across various devices is paramount. Cascading Style Sheets (CSS) play a crucial role in achieving this by defining the visual presentation of your website. But with the ever-evolving landscape of screen sizes and user preferences, ensuring consistent and responsive design can be challenging.

This is where REM units (short for "root em") come in as a game-changer. REMs offer a dynamic approach to defining element sizes in CSS, making your website more adaptable and user-friendly.

What are REM Units?

Unlike pixels (px), which represent a fixed size, REM units are relative to the font size of the root element (html). By default, most browsers set the html element's font size to 16px. Therefore, 1rem is equivalent to 16px. This creates a crucial link between your base font size and other elements on your website.

Here's the breakdown:

  • 1rem = font-size of the root element (usually 16px)
  • 2rem = 2 x font-size of the root element (usually 32px)
  • 0.5rem = 0.5 x font-size of the root element (usually 8px)

Why Use REM Units?

Here's how using REM units can significantly improve your website:

Scalability: REM units allow for responsive design by enabling you to scale font sizes and other elements proportionally based on the user's device or browser settings. Users can adjust their preferred font size in their browser and the entire website will adjust accordingly, maintaining a consistent layout and user experience.

Maintainability: Using REM units simplifies CSS maintenance. Changing the base font size in the html element automatically applies the change to all elements defined using REM units. This saves you time and effort when making website-wide adjustments.

Consistency: REM units ensure consistent relative sizing across different elements. This creates a visually balanced and aesthetically pleasing website.

Accessibility: REM units are particularly beneficial for users with visual impairments who may rely on browser zoom features to enlarge website content. Since REM units scale proportionally, the website remains visually appealing and usable even when zoomed in.

How to Use REM Units Effectively:

Set the Base Font Size: Establish a base font size for your html element. This will serve as the foundation for all your REM-based sizing.

Define Element Sizes in REM: Instead of using pixels (px) to define element sizes, use REM units. For example, instead of font-size: 16px;, use font-size: 1rem;.

Maintain a Consistent Hierarchy: Use a logical hierarchy for font sizes across different elements (headings, paragraphs, buttons, etc.). This ensures visual clarity and guides user navigation.

REM vs. EM Units:

It's important to distinguish REM from another relative unit – EM (ems). While both are relative, EM units are based on the font size of the parent element, whereas REM units are based on the font size of the root element. This can lead to potential inconsistencies when elements are nested within each other deeply. Generally, REM units offer more predictable and manageable scaling across the entire website.


REM units offer a powerful and flexible approach to website design. By embracing REM units in your CSS workflow, you can create websites that are not only visually appealing but also adaptable to diverse user preferences and screen sizes. So, ditch the pixel limitations and embrace the dynamic world of REM for a future-proof web design experience.

Ready to take your website's responsiveness to the next level? Our team of web development experts at Uniworld Studios can help you implement REM units and other best practices to create a website that scales beautifully across all devices.  Contact us today for a free consultation!