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What is CSS Architecture?

101 Guide on CSS Architecture

Do you remember the Internet's early times? All pages were pretty much the same. They all had two or three same colors, fonts, and designs. Yet, you will also remember how pages' format and content started evolving. As a result, various structures appeared for websites, blogs, and social networks. Also, sites began to adapt to ever-going new formats. For instance, we have seen sites' appliances for smartphones, tablets, and smartwatches. 

By now, we know that people expect a site to be appealing. This concept applies to future customers, companies to associate with, and potential employees. As for 2022, sites must not only "look nice." Also, they need to be functional and efficient. There is a lot of information to collect and process in each interaction with each user. In this context, we'd like to share a timeline of CSS architecture. We know this style language is a must-go for design improvements from a development stand. We'll explore its story, uses, and how it can adapt to your work's needs. Let's start this journey!

What is CSS?

CSS are the initials of Cascading Style Sheets. It's a style language within Front-End Development, often in HTML documents. It works to describe how HTML elements should display. Since its beginnings, around 1995, it has gone through significant changes. Within its structure, it updates and develops ever-evolving properties. These include sizes, colors, style fonts, border styles, background images, and more. In consequence, it keeps including advanced features according to different market needs.

As we said above, CSS has a strong bond with HTML. Let's put it this way: HTML's work provides structure and meanings, or what elements will appear. In parallel, CSS specifies how those elements will look, display, and present. In other words, HTML and CSS can do amazing things together! For instance, devs can write HTML docs without thinking of their display. Instead, they can use CSS to define it in parallel or after finishing the structure. Yet, that's not it! They also can change CSS content while maintaining HTML untouched. In summary, form, and style can stay connected and perform separate modifications.

What is CSS Architecture

What is CSS Syntax?

We've talked about what CSS is and how it works. Now, we'll go ahead with its basic syntax. With this, we can unfold why its architecture has so much relevance. 

CSS syntax is a set of rules with four parts. These elements are selectors, declarations, properties, and values. Selectors represent the HTML element you aim to style. Also, they can apply to as many aspects as it's needed. For that, devs only need to separate selectors with a comma. These must separate each declaration with a semicolon to use more than one property. They also can make the code more readable by spreading assertions across the lines. These properties don't affect the code's render: they only make it more readable for devs. In summary, CSS applies rules assigned to  HTML elements. These rules get processed by browsers when loading HTML files. Let's unfold its parts:

CSS Selectors

Every CSS rule starts with a selector. Those states in which part of the document will different restrictions apply. After specifying selectors, there are one or more statements between parentheses. There are many ways to write these selectors. Its most basic  method is mentioning elements by name and then modifying them. Yet, you can also call these elements by their class or attribute.

CSS Declarations

After specifying a selector, it gets followed by a declaration block. Each block sets the given style for the selected element. This process unfolds through two variables: properties and values. Within this logic, each declaration gets written in a different line. As a result, these are easier to locate, read, and rewrite.

CSS Properties and Values

Different properties have a variety of values assigned. These specify how the style these will have. Let's name a few examples. For instance, color properties can have different values. These values include words like red or blue, hex code values like #33E0FF, or RGB like (51, 224, 255). Width properties can have px, cm, em, or percentage values to define elements' size. Last but not least, font style properties can have known font names, like Arial, Times New Roman, or Courier. Yet, you can connect documents with plugins or third-party platforms to expand options.

On top of declaration formats and elements, CSS needs a connection with HTML. For this, there are two standard linking ways: external and internal. In external links, the CSS has its document, which then connects through a tag to the HTML doc. Since this method enables writing the style of many different HTML docs, it's the most used one. Thus, it allows devs to make changes all over the site with one CSS document. Yet, in internal links, CSS is within the HTML document. And often, it fits small projects and specific pages better. 

Another concept with enormous relevance within the CSS syntax is its Cascades. Yes, the ones that give the C to CSS. In its Cascades, CSS acknowledges the elements' order when providing its final style. If a property has many assigned values, browsers process the last valid one. This method prevents risks of coexistent yet conflicted rules in a document. As a general concept, this applies to both internal and external CSS documents. Yet, how can you use this syntax for larger companies with lots of data to process? That's what brings CSS Architecture to the table. 

What is CSS Architecture?

As a style language, CSS is simple to learn and understand in its basic form. Yet, with more complex projects, it can get a little bit trickier. Due to its potential complexity, code can get messy with larger sheets. The key to preventing untidiness is knowing the relevance of organizing CSS documents. Thus, it's fundamental for devs to apply standard practices to improve maintainability. As a result, CSS stylesheets will have a consistent unity.

These are usually style guides: guidance structures to establish consistency through a document. With this approach, a complex design can become much more manageable. That's because it helps code become more scalable, flexible, and reusable. Also, it leaves behind the idea of designing many pages individually. A CSS Architecture can apply on many levels. There are three main steps when structuring CSS:

1. Breaking code into smaller chunks and separating them by scope.
2. Coding components in independent and encapsulated manners.
3. Naming CSS selectors according to their purpose and relationship with each other.

When defining CSS classes, the name affects the global scope. While it's great for simple apps, it can become problematic when the project's size grows. In this context, the concept of CSS Architecture rises to make devs' lives easier. Yet, sometimes it can be counterintuitive for code's reusability. 

In the beginning, there were some pre-established solutions. Some of them included SASS or LESS variables. Yet, nowadays, the majority of browsers support custom CSS properties. This latter solution offers two essential benefits. One allows code modifications at runtime. When switching themes, for instance, this method is a perfect solution. Other solutions relate to the layout components. With custom CSS, modifications can occur within it. As a consequence, devs can adjust the design on a smaller scale.

While you can create your own, devs often apply one of the most known methodologies. Among the most used are OOCSS, BEM, and SMACSS. These are already tested and optimized, ensuring security and time-saving.

What is CSS Architecture?

Helpful CSS Architecture Tools

CSS has many available tools. There are tons of updated data that upgrade how to work with it. In this context, an element to pay attention to is Resets, like ResetCSS and Normalize.CSS. The first one will wipe out all built-in styling for HTML elements. Meanwhile, the second one will remove browser inconsistencies with HTML. Instead of removing everything, like CSS Reset, Normalize.CSS preserves valuable defaults. Another popular tool is CSS Preprocessors. Within these, it's possible to generate code from a unique syntax. Also, it includes features such as mixins, functions, and nestings. Some examples of this include Sass with SCSS syntax and PostCSS. These will make code easier to read and maintain.​​

We already know that technologies are spreading into many new devices and formats. In this context, CSS is and will be adapting. Currently, there are many unique properties and values developed to guarantee adaptability. Also, more variable fonts allow customization. And further, there's a new collection of browser APIs called CSS Houdini. This concept is a new W3C task force aiming to erase browser support issues. As a result, it allows devs to gain control and access to the browser's CSS engine.


CSS started as the style language to work with HTML documents. Now, we see that it's approaching more complex tasks and projects. These tasks go from establishing syntaxes to adapting to more extensive proposals. Since its beginnings, we have used CSS to get the structure for appealing web pages and apps. Yet, now we can use it with better features and more manageable code ways. We hope this article helps you to have a more profound knowledge of how CSS architecture works. We're also excited to see how its future unfolds!