CSS (Cascading Style Sheets) is a style sheet language used to add visual effects to web pages. It is used to describe the page layout and display of HTML elements. You can save a lot of time with CSS. Use it to manage the layout of multiple web pages at the same time. It enables developers to implement various custom properties for different elements, thus enhancing the appearance of web pages. In this article, we will learn about CSS and how it works.
CSS is basically divided into 3 types -
External CSS - On every page, use the element and the link> tag belongs to the head section. If you want to change multiple pages at the same time, use an external style sheet. It is very useful in this situation because it enables you to change the appearance of the entire website by modifying just one file.
Inline CSS - If a single HTML page has a unique style, you can use an internal style sheet. The style> element in the head section contains the definition of internal styles.
Internal CSS - To give individual elements a unique look, use inline styles. Use inline styles by adding the style attribute to the appropriate element. The style attribute is a container for any CSS property.
selector{
property: value;
}
Given below is an example of how to use CSS in an HTML page. Here we have inline CSS. The h1 element is underlined, while the div element is green.
<!DOCTYPE html>
<html>
<head>
<title> Using CSS within a HTML page </title>
<style>
h1{
text-decoration: underline;
}
div{
width: 30%;
height: 30px;
background-color: green;
}
</style>
</head>
<body>
<h1> Inline CSS </h1>
<div> This is an example. </div>
</body>
</html>
Save Time- It saves a lot of time. Because CSS style definitions are kept in separate CSS files, changing one of them can have an impact on the entire website.
Multiple Attributes - CSS provides more precise options for determining the look and feel of a website than plain HTML.
Fast Page Loading- When using CSS, it is not always necessary to write HTML tag attributes. You can write a rule once for a label and apply it to all instances of that label. Since CSS uses less code, it downloads faster.
Website Maintenance- The website requires it for maintenance. If we need to make a global modification to the file, we can simply change the style and all components on the web page will be updated immediately. Due to the flexibility of CSS files, the design of a website can be easily modified.
Multi-Device Compatibility - We can use CSS with previous language versions because it is traditionally compatible with them. Therefore, if a CSS application was created using an earlier version of the programming language and the developer merges it with newer development content, CSS can be easily integrated with the required adjustments, allowing the developer to successfully update the existing code. Content using CSS can adapt to multiple device types.
The actual process of calculating the final CSS properties for a given HTML element is an extremely complex series of steps -
At this stage, all style declarations for a specific element are collected from various sources such as user agents, authors, and users. These declarations must be filtered and validated to determine whether they come from a style sheet that now applies to this document and are syntactically valid.
The word CSS stands for Cascading Style Sheets, which is the basic concept of CSS. This stage must be understood thoroughly because it is the only stage that is deeply influenced by the developer as authorial source. This stage takes the unordered list of claims collected in the previous step and sorts them in descending order of priority using the following criteria -
Based on declaration source (user agent, user, author, transition, animation) and! A combination of important notes.
Speciality based on selector
Based on the order in which they are written
If not declared, this step is called when trying to set a value for the element's CSS property.
For maximum flexibility in responsive design, we use several relative units (auto, em, rem, vh), relative URLs, percentages, or certain human-readable keywords (small, normal, bold body). This stage will attempt to resolve as many attribute values as possible without having to place a document, perform a network query, or get the value from somewhere other than the parent.
This stage will format the entire document and complete the remaining work from the previous step by trying to calculate the absolute theoretical values used in the document layout. This stage mainly focuses on scenarios such as relative coordination of elements, automatic layout, and Flex layout. It requires many calculations but produces an absolute number that is almost completely usable for browsers to use.
Before drawing, the final stage will perform some modifications based on the surfing environment, such as browser engine, media type, device pixel density, or operating system. Rounding floating point numbers to integer values or changing the font size based on available fonts are two common changes.
Since CSS cascading is one of the most misunderstood aspects of CSS (and is often the source of many mistakes), understanding how it works will give you a significant advantage in keeping your stylesheet manageable. However, the greater the understanding of the CSS cascade, the greater the responsibility. The more specialized parts of the cascade (such as !important, inline styles, and id selectors) produce stylesheets that are more difficult to change or override in the future.
The above is the detailed content of 'How does CSS work behind the scenes?'. For more information, please follow other related articles on the PHP Chinese website!
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
