What is CSS? Learn web development MDN
CSS provides five special universal property values for controlling inheritance. External style sheets can be referenced with a full URL or with a path relative to the current web page. The CSS border property defines a border
around an HTML element. The CSS font-family property defines the font to be used.
- You might have seen a website that fails to load completely and has a white background color with most of the text being blue and black.
- We strive for simplicity and accuracy with every definition we publish.
- CSS stands for Cascading Style Sheets, and that first word cascading is incredibly important to understand — the way that the cascade behaves is key to understanding CSS.
- We’d advise that you return to this article a few times as you continue through the course, and keep thinking about it.
The selector points to the HTML elements you want to style. The declaration block contains one or more declarations separated by semicolons. That’s what web pages with only HTML look like, and I think you’d agree that that’s not very appealing.Before using CSS, all of the stylizing had to be included into the HTML markup. This means web developers had to separately describe the background color, font size, alignments, etc. CSS properties have different allowable values, depending on which property is being specified. In our example, we have the color property, which can take various color values.
External CSS
Because I couldn’t be bothered to figure out how they produced an effect I liked, I just linked to their code. I’m pretty sure that was completely legal, by the way, but I definitely don’t recommend you try it. It’ll only be a matter of time before they make some changes to their style sheet that breaks your site. Cascading style sheets, known universally as CSS, aren’t really sheets, and it can take some work to figure out what “cascading” means. But the markup standard adds real power to your web development work. When tags like , and color attributes were added to the HTML 3.2
specification, it started a nightmare for web developers.
This means that the code has been written to turn the instruction in our CSS file into something that can be output to the screen. We’ll look at this process more in the lesson How CSS works. It is unusual for all browsers to implement a feature at the same time, and so there is usually a gap where you can use some part of CSS in some browsers and not in others.
Internal, External and Inline CSS Styles
You will find that you quickly learn some values, whereas others you will need to look up. The individual property pages on MDN give you a quick way to look up properties and their values when you forget or when you want to know what else you can use as a value. As we have mentioned before, CSS is a language for specifying how documents are presented to users — how they are styled, laid out, etc. However, the web would be a boring place if all websites looked like that. Using CSS, you can control exactly how HTML elements look in the browser, presenting your markup using whatever design you like. First of all, we are only interested in the first seven rules of this example, and as you’ll notice, we have included their specificity values in a comment before each one.
The following table shows a few isolated examples to get you in the mood. Try going through these, and make sure you understand why they have the specificity that we have given them. We’ve not covered selectors in detail yet, but you can find details of each selector on the MDN selectors reference. We can look at a list of links and explore how universal values work. The live example below allows you to play with the CSS and see what happens when you make changes. Playing with code really is the best way to better understand HTML and CSS.
CSS syntax
We now understand that inheritance is why a paragraph nested deep in the structure of your HTML is the same color as the CSS applied to the body. From the introductory lessons, we have an understanding of how to change the CSS applied to something at any point in the document — whether by assigning CSS to an element or by creating a class. We will now look at how cascade defines which CSS rules apply when more than one style block apply the same property, but with different values, to the same element.
CSS is a powerful tool that gives web designers flexibility and modularity in the presentation layer of a web site. Transitions add smooth animations to elements, enhancing user experience. Flexbox is a layout model that simplifies the design of complex layouts. It’s perfect for building flexible and responsive structures. Let’s start by taking a quick look at the key things we are dealing with, then we’ll look at each in turn and see how they interact with each other and your CSS.
Cascading Style Sheets Explained In a Video Tutorial
Specificity between layers doesn’t matter, but specificity within a single layer still does. CSS is a style sheet language used for formatting content in HTML webpages. CSS style sheets can define the appearance and formatting of text, tables, and other elements separately from the content itself. Styles may be found within a webpage’s HTML file or in a separate document referenced by multiple webpages.
The best way to evaluate specificity is to score the specificity levels individually starting from the highest and moving on to the lowest when necessary. The first has styling applied to the blockquote element itself. The second has a class applied to the blockquote, which sets the value of all to unset. Resets the property value applied to a selected element to the browser’s default styling rather than the defaults applied to that property. The CSS font-size property defines the text size to be used. The CSS color property defines the text color to be used.
Let’s discuss a few things from the above example to understand what’s happening. Two layers have been declared, firstLayer and secondLayer, in that order. Even though the specificity in secondLayer is the highest, no properties from that declaration are used. Stylesheets cascade — at a very simple level, this means that the origin, web development css cascading the cascade layer, and the order of CSS rules matter. When two rules from the same cascade layer apply and both have equal specificity, the one that is defined last in the stylesheet is the one that will be used. The styles described by CSS include the colors, fonts, layout, and other presentation aspects of a document.
Finally, it is important to note that the precedence of a CSS declaration depends on what stylesheet and cascade layer it is specified in. With the basics of the CSS language covered, the next CSS topic for you to concentrate on is styling text — one of the most common things you’ll do with CSS. Here we look at text styling fundamentals, including setting font, boldness, italics, line and letter spacing, drop shadows, and other text features. We round off the module by looking at applying custom fonts to your page, and styling lists and links.
And CSS adds more sophisticated control over the way that content looks and behaves. Media queries enable you to apply different styles based on the characteristics of the device. Now that you have some understanding of what CSS is, let’s move on to Getting started with CSS, where you can start to write some CSS yourself. Presenting a document to a user means converting it into a form usable by your audience. Browsers, like Firefox, Chrome, or Edge, are designed to present documents visually, for example, on a computer screen, projector, or printer. CSS (Cascading Style Sheets) allows you to create great-looking web pages, but how does it work under the hood?
