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What are CSS Frameworks?

Learn everything you need to know about CSS frameworks here!

Table of Contents & All Terms

A company that wants its branding consistent across all digital channels and devices will codify its branding style choices in a design system and style guide. From a technical point of view, a CSS framework converts those style choices into coded components that designers and engineers can use to build digital assets. This CSS code is inserted directly into the software or added to the CMS platforms that designers and marketers use to create content.

For example, if the designers want to see a particular rare blue or in-house-designed font on all web pages, the pre-built CSS code in their framework will guarantee that. If all graphical imagery placed on a website must follow size and space rules, a company-wide CSS framework implements that.

What is a CSS framework?

First, CSS—Cascading Style Sheets—refers to a set of files with specialized code that defines the styles and interactive elements that developers can insert into the front-end code and use to build their user interfaces (UI). CSS code is a simple, script-like set of directives that determines all the visual aspects of web and mobile pages.

Thus, in its simplest form, a CSS framework (learn about the most popular frameworks here) is a collection of CSS stylesheets that contain ready-to-use, pre-built styles and interactive components.

On the style side, the framework establishes a grid structure to organize on-screen information or manage responsive web design. It also defines a website's typography, icon fonts, 2D and 3D graphic elements, and styling for text, buttons, and other page elements.

The interactive elements contains the code that defines the style and behavior of the popup modal windows, tabs, slides, or accordion-like menus.

What are grids, responsive design, and components?

You can integrate your CSS framework into your Content Management System (CMS) and design your web pages based on your framework's grids, responsiveness, and components.

Let's look at some of these elements in more detail.

A grid system is a flexible layout of rows and columns that helps organize and position the elements on a web page.

For example, you can build a Prismic blog as a 3x3 grid (three columns and three rows), resulting in 6 cells. The three columns will contain the left-side menu, another for the middle text, and the last for clickable imagery and promotions. The three rows will include the top menu and hero section, the middle for the text, and the bottom for a lower-third blog section. The rows and columns do not have to be the same width and height. The middle text column on a blog will typically be larger than the left, right, top, and bottom cells.

A responsive design ensures the grid layout adapts to different desktop, tablet, and mobile screen sizes. The idea is that the 3x3 grid remains 3x3 regardless of the screen size. But, responsive design may also change the grid: mobile is 1x1, while all desktops are 3x3.

The components in a CSS file are pre-designed UI components that determine the look and feel of navbars, modals, tooltips, carousels, and more. There are also JavaScript components—coded scripts that manage the behavior of modals, tooltips, dropdowns, accordions, tabs, and other interactive elements.

Benefits of using a CSS framework

CSS frameworks offer speed

The number one selling point for using a CSS framework, especially a time-tested, robust third-party framework, is the speed at which it goes live with a finished product. CSS frameworks speed up development and delivery by providing ready-made styles and components.

However, time-saving is not its only advantage. There are others.

CSS frameworks offer cross-browser compatibility

Developers don’t have to spend countless hours managing the different kinds of browsers that exist. CSS frameworks manage the tedious differences between Google Chrome, Apple Safari, and Mozilla Firefox. And they keep up with updates on these browsers.

CSS frameworks offer consistency

As mentioned in the opening paragraph, consistency is key to branding, and using a company-wide CSS framework ensures a consistent look and feel across a website's different pages. On this point, a CSS framework offers a solid basis to customize to create unique branding.

Examples: Third-party and in-house CSS frameworks

As suggested, companies can start with an already-built framework, such as the popular Bootstrap, Foundation, Bulma, and Tailwind CSS frameworks. Companies can use these frameworks out-of-the-box and customize them to create a unique look, feel, and branding.

Third-party frameworks enable fast go-live and easy style updates, such as fonts, colors, margins, spacing, button shapes, behavior, etc. They also keep you in line with the latest technologies. They provide common web elements, the newest CSS features, and trending web elements.

That said, since a framework is a set of CSS files with CSS and JavaScript code, a company can start from scratch. Or they can customize a publicly available framework to the point that it is no longer recognizable in its original form. This is done for highly motivated companies with specific needs and the engineering resources to create and maintain their own framework.


A powerful CSS framework will offer pre-built, coded components that help any company quickly build consistent, responsive, and engaging websites. A framework includes everything from a responsive grid system, common styles, and components with the newest and most advanced CSS and web technology, making a framework invaluable for achieving a powerful online presence.