In that module, you will also find a link to Specifications that defines the technology (also see the section below). CSS is a rule-based language — you define the rules by specifying groups of styles that should be applied to particular elements or groups of elements on your web page. In the Introduction to HTML module, we covered what HTML is and how it is used to mark up documents.
Tags like were introduced in HTML version 3.2, and it caused quite a lot of trouble for web developers. Due to the fact that web pages have different fonts, colored backgrounds, and multiple styles, it was a long, painful, and expensive process to rewrite the code. As there are so many things that you could style using CSS, the language is broken down into modules. You’ll see reference to these modules as you explore MDN. Many of the documentation pages are organized around a particular module. For example, you could take a look at the MDN reference to the Backgrounds and Borders module to find out what its purpose is and the properties and features it contains.
CSS SASS
Development of large
websites, where fonts and color information were added to every single
page, became a long and expensive process. If you didn’t fully understand the cascade, specificity, and inheritance, then don’t worry! This is definitely the most complicated thing we’ve covered so far in the course and is something that even professional web developers sometimes find tricky.
This module carries on where CSS first steps left off — now you’ve gained familiarity with the language and its syntax, and got some basic experience with using it, it’s time to dive a bit deeper. This module looks at the cascade and inheritance, all the selector types we have available, units, sizing, styling backgrounds and borders, debugging, and lots more. 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. Having everything on one page makes it easier to share the template for a preview.
CSS Border
Sets the property value applied to a selected element to the initial value of that property. 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. OK maybe that’s a slight exaggeration, but it’s far more amenable to non-code, non-programming people who are just starting web development css cascading out than any notion of a cascade, or inheritance. This module provides links to sections of content explaining how to use CSS to solve common problems when creating a web page. The aim here is to provide you with a toolkit for writing competent CSS and help you understand all the essential theory, before moving on to more specific disciplines like text styling and CSS layout.
- This means web developers had to separately describe the background color, font size, alignments, etc.
- We encourage you to work through this section carefully and check that you understand the concepts before moving on.
- Let’s discuss a few things from the above example to understand what’s happening.
- It separates the content from the visual representation of the site.
- The CSS border property defines a border
around an HTML element.
If you’re new to web development, be sure to read our CSS basics article to learn what CSS is and how to use it. CSS lets you have multiple styles on one HTML page, therefore making the customization possibilities almost endless. Nowadays, this is becoming more a necessity than a commodity. CSS is not technically a necessity, but you probably wouldn’t want to look at a web page that features only HTML elements as it would look completely bare-boned.
Resetting all property values
We already know that an element selector has low specificity and can be overwritten by a class. Essentially a value in points is awarded to different types of selectors, and adding these up gives you the weight of that particular selector, which can then be assessed against other potential matches. You will often run into a situation where you know that a rule comes later in the stylesheet, but an earlier, conflicting rule is applied. This happens because the earlier rule has a higher specificity — it is more specific, and therefore, is being chosen by the browser as the one that should style the element. Resets the property value applied to a selected element to the value established in a previous cascade layer.
Consult the information in that table to check if the property can be used on your website. For an example, see the browser compatibility table for the CSS font-family property. To solve this problem, the World Wide Web Consortium (W3C) created CSS. If you understood most of this article, then well done — you’ve started getting familiar with the fundamental mechanics of CSS.
CSS Saves a Lot of Work!
We’d advise that you return to this article a few times as you continue through the course, and keep thinking about it. Even though cascade layers is an advanced topic and you might not use this feature right away, it’s important to understand how layers cascade. For example, if you set a color and font-family on an element, every element inside it will also be styled with that color and font, unless you’ve applied different color and font values directly to them. Inheritance also needs to be understood in this context — some CSS property values set on parent elements are inherited by their child elements, and some aren’t. If you include two stylesheets and there’s a rule with the same specificity in each, the one included last wins. When I teach CSS, I always tell the students that «cascading style sheets» means something like «fighting style sheets».
If you put a rule on any tag inside the body it will adopt that rule, and so on. So the rule cascades through all the content unless interrupted by a rule from an embedded tag. Now imagine that every step is representing a differently placed rule that can apply style to your HTML.
HTML and CSS
Each declaration includes a CSS property name and a value, separated by a colon. A CSS declaration always ends with a semicolon, and declaration blocks are surrounded by curly braces. CSS was developed by W3C (World Wide Web Consortium) in 1996 for a rather simple reason.
These can seem like a tricky set of concepts to understand. As you get more practice writing CSS, the way it works will become more obvious to you. It can control the layout of multiple
web pages all at once. If you have a rule that that is on the body tag it will «cascade» through every child tag.
Cascading Style Sheets/Introduction
It is possible for users to set custom stylesheets to override the developer’s styles. For example, a visually impaired user might want to set the font size on all web pages they visit to be double the normal size to allow for easier reading. At some point, you will be working on a project and you will find that the CSS you thought should be applied to an element is not working.