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Introduction to Cascading Style Sheets

Introduction to Cascading Style Sheets

min read
Published on
January 20, 2024


In the ever-evolving landscape of web development, creating visually appealing and user-friendly web pages is a top priority. One of the fundamental technologies that empower web developers to achieve this is Cascading Style Sheets, more commonly known as CSS. 

CSS is a style sheet language that determines how web content is presented and styled. In this resource, we will explore the basics of CSS, how it works, and its importance in the realm of web design.

What is CSS?

CSS, which stands for Cascading Style Sheets, is a style sheet language used to describe the presentation of documents written in HTML or XML (Extensible Markup Language). Essentially, it's the tool that allows developers to control the look and feel of their web pages. When a web page is loaded, the browser interprets the HTML or XML content and then applies the CSS rules to determine how that content should be displayed. 

HTML serves as the fundamental building block of a website, while CSS is responsible for the visual design and aesthetics of the entire site. Their relationship is tightly intertwined, as HTML establishes the structural groundwork, and CSS governs the overall appearance and style of the website.

How Does CSS Work?

CSS functions by targeting individual elements within a webpage and dictating their visual presentation and layout. It does so by employing selectors that pinpoint these elements and then applying rules that specify their appearance. For instance, it can define the colours, fonts, spacing, and positioning of elements.

Selectors in CSS can range from simple elements like headings (h1, h2, etc.) and paragraphs to more complex structures such as classes and IDs, enabling precise and granular control over the design and style of a webpage. Since Webflow is a visual development tool, it enables the user to control the CSS code visually which can make the process a lot easier.

Here's how it works…

Styling Rules

CSS is what makes a website look visually appealing. These styles are like a set of instructions that tell a web browser how to display elements on a web page. They're written in a separate file with a ".css" extension or can be directly included within the HTML file using the <style> tag.

Imagine these styles as a set of rules or guidelines for the web browser to follow when displaying a webpage. Each rule consists of two main parts: a selector and a declaration block.


Selectors are like the web browser's search queries—they pick which HTML elements the style rules will be applied to. Selectors can be specific, targeting elements like headings (h1, h2, etc.), paragraphs, or images. They can also be more general, applying to entire classes of elements or specific IDs. Selectors are a crucial part of CSS as they determine which elements should be styled.

Declaration Block

Once a selector identifies the elements to style, the declaration block contains the actual styles to be applied. This block includes property-value pairs that define how the selected elements should look. For example, it could specify the font, colour, size, margins, or positioning of elements.

Properties and Values

Once an element is selected, CSS properties and values are used to define how that element should appear. For instance, you can set the font size, background colour, margin, and more. A colon and its corresponding value follow each property.

An example of a CSS rule might look like this:


h1 {

  colour: blue;

  font-size: 24px;


In this example, h1 is the selector that targets all the heading 1 elements. Colour and font size are properties, and blue and 24px are their respective values.

These rules allow you to get creative with how your webpage looks. You can change colours, fonts, spacing, and more to create a unique style that matches your design preferences or brand identity. Whether you're making the text more readable, adding spacing between elements, or changing colours, CSS provides the tools to make your website look just the way you want.

Webflow has it’s very own code block inserter meaning you can add code snippets to any page on your Webflow site. The process is easy to grasp; you simply copy the code you'd like to display in the code block, open the Add panel, navigate to Advanced, drag a code block to the canvas, paste your code into the code editor, and finally, click Save & close. This straightforward method allows you to seamlessly integrate custom code elements into your Webflow site.

Image of Webflow's code block. Shows:Custom Code:1. <pre><code class="langauge-css">.test {2. display: block;3. text-align: centre;4. }</code<>/pre>
Image Credits: HTML All The Things

The Cascade

The term "Cascading" in CSS refers to how the styles are applied. The cascade algorithm determines the priority of styles when multiple rules conflict. CSS properties can be inherited from parent elements, specified in a style sheet, or even set by the user, and the cascade ensures that the most specific rule takes precedence. It helps maintain order and consistency in styling.

Understanding the cascade is essential to mastering CSS. It defines how user agents (browsers) combine property values originating from different sources and ensures that the final appearance of an element is predictable and consistent.

When multiple CSS rules target the same element and conflict, the cascade resolves these conflicts based on specificity and origin precedence. For example, a CSS rule defined in an inline style attribute will take precedence over an external style sheet rule, even if the inline rule has lower specificity. This is just one example of how the cascade ensures that the most appropriate styles are applied.

The Importance of CSS in Web Development

As we’ve covered, CSS plays a pivotal role in the realm of web design, influencing the overall look, feel, and functionality of websites. It is the language used to control the visual aspects of a website. It determines how elements appear on a page, including the colour, typography, layout, and overall style. Using CSS, web designers can create visually appealing and aesthetically pleasing websites that captivate and engage visitors.

Here are some ways CSS is important in web development…

Consistency and Efficiency

CSS allows for consistency in design across a website. By defining styles in a central stylesheet, designers can ensure uniformity in design elements throughout the site. This not only simplifies the process of updating and modifying styles but also makes the website visually coherent, offering a seamless user experience.

Adaptability and Responsiveness

With the increasing diversity of devices used to access the internet, responsive web design has become crucial. CSS enables websites to be responsive, adapting their layout and appearance based on the device's screen size. This adaptability ensures a consistent and user-friendly experience across various platforms, including desktops, tablets, and mobile phones.

User Experience and Accessibility

A well-structured and aesthetically pleasing website enhances the user experience. CSS allows designers to create layouts that are not only visually appealing but also easy to navigate and understand. Furthermore, it facilitates accessibility by enabling designers to optimise websites for users with disabilities, making content more accessible and inclusive. If you want to know more about optimising your Webflow website for accessibility and inclusivity, have a read our blog: How to Optimise Your Webflow Website for Accessibility and Inclusivity

Search Engine Optimisation (SEO)

While CSS primarily focuses on design, it indirectly impacts SEO. Well-structured and properly formatted CSS can improve site performance, which is a crucial factor in search engine rankings. A clean, efficient code structure created with CSS can positively influence load times and overall user experience, contributing to better SEO.

Brand Representation

CSS provides an opportunity for brands to showcase their identity. Designers can use CSS to convey a brand's personality, values, and messaging through visual elements, ensuring that the website aligns with the brand's image and voice.


In essence, Cascading Style Sheets (CSS) is a cornerstone technology that enables developers to create visually appealing, responsive, and user-friendly web pages. By separating the presentation (CSS) from the content (HTML), web developers can ensure a consistent look and feel across their sites while adapting them to different screen sizes and device types.

Mastering CSS involves understanding selectors, properties, and the cascade. It allows developers to create sophisticated designs and responsive layouts, making the web a more engaging and enjoyable experience for users. So, whether you're a seasoned developer or just starting your journey in web development, gaining proficiency in CSS is an indispensable skill that will open the door to creating beautiful and functional web pages.

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