Learn Web Development Basics HTML, CSS, and JavaScript Explained for Beginners

CSS is a style sheet language responsible for the presentation of documents written in a markup language. CSS code can start to get complicated once you start applying different styles for various devices, screen sizes, resolutions, and more. In addition, one of the greatest challenges with CSS is that what is css it is not uniformly supported by different web browsers like Firefox, Safari, and Chrome. That means a web page with the same stylesheet might not look the same on different devices or web browsers. HTML (HyperText Markup Language) is the code that is used to structure a web page and its content.

Based on the above explanation, we know that the browser will begin by parsing the HTML. This process will lead to the creation of the above DOM from the previous section, then parse the CSS. The CSS only has a single rule, which uses a span selector. As such, that rule will apply to every occurrence of in the HTML, of which there are two. There is no single, integrated CSS4 specification,[52] because the specification has been split into many separate modules which level independently.


Since both HTML and CSS have a strong impact on how information appears, it’s crucial to understand the impact that CSS has on HTML. Simply put, web browsers follow CSS rules to determine how a document should be displayed. CSS styles done this way are loaded each time an entire website is refreshed, which may increase loading time. Additionally, you won’t be able to use the same CSS style on multiple pages as it’s contained within a single page.

what is css in html

And you can use this great Intro to JS course to supplement your learning. Your brain has been programmed to react in a certain way or do certain things whenever something happens. In this same way, you can program your web page or individual elements to react a certain way and to do something when something else (an event) happens. We access each of the elements we want to work on by “selecting” them. The h1 selects all level 1 headings in the page, the h2 selects the level 2 elements, and so on. You can select any single HTML element you want and specify how you want it to look or be positioned.

Learn to style HTML using CSS

In the Styling a biography page assessment you’ll use your new knowledge to restyle an example, testing out some CSS in the process. Similarly, if a browser encounters a selector that it doesn’t understand, it will just ignore the whole rule and move on to the next one. In our Debugging CSS article in the next module we will be using browser DevTools to debug CSS problems, and will learn more about how the browser interprets CSS. Click on the Stylesheet buttons (1-4) too see the page displayed with different styles. The declaration block (in curly braces) contains one or more declarations separated by
semicolons. This module provides links to sections of content explaining how to use CSS to solve common problems when creating a web page.

  • Modules that build on things from CSS Level 2 started at Level 3.
  • A markup language is used to define the text document within tag which defines the structure of web pages.
  • For an example, see the browser compatibility table for the CSS font-family property.
  • The displaySum is a function which gets both items from the web page, converts them to numbers (with the Number method), sums them up, and passes them in as inner values to another element.
  • New browsers will interpret the line using pixels, but then override it with the line using calc() as that line appears later in the cascade.

You can check out the second part of freeCodeCamp’s Responsive Web Design certification to get started. You can also use CSS to layout elements by positioning them in specified areas of your page. If you are building anything other than a demo, you will need to add some basic styling to make it more presentable. In this article, I will explain the basics of what HTML, CSS, and JavaScript are, how they make the Web work, and what they do on their own. You’ll also discover that websites are mostly built from these three languages.