What is CSS? 

CSS stands for Cascading Style Sheets. It is a stylesheet language used to describe the presentation of a document written in HTML  or XML  (including XML dialects such as SVG , MathML , or [XHTML]). CSS describes how elements should be rendered on screen, on paper, in speech, or on other media.

 

Here are some key points about CSS:

• Separation of Content and Presentation: CSS allows you to separate the content of your web pages (HTML) from the presentation (CSS). This makes it easier to maintain and update your website.
• Selectors and Properties: CSS uses selectors to target HTML elements and apply styles to them. Properties define the styles, such as color, font, and layout.
• Cascading and Specificity: The "Cascading" in CSS refers to the way styles are applied based on their specificity and order. More specific rules override more general ones, and later rules override earlier ones if they have the same specificity.
• Responsive Design: CSS includes features like media queries that allow you to create responsive designs that adapt to different screen sizes and devices.

 

What is the mean of cascading?

In the context of CSS, "cascading" refers to the way styles are applied to HTML elements based on a hierarchy of rules. The term "cascading" is used because multiple styles can be applied to the same element, and the final style is determined by a set of rules that "cascade" down to determine which style takes precedence.

 

Here are the key concepts that explain how cascading works:

• Inheritance: Some CSS properties are inherited from parent elements to child elements. For example, if you set the color property on a parent element, its child elements will inherit that color unless they have their own color property set.
• Specificity: CSS rules have different levels of specificity. More specific rules will override less specific ones. Specificity is calculated based on the types of selectors used:
  Inline styles (e.g., style="color: red;") have the highest specificity.ID selectors (e.g., #header) are more specific than class selectors (e.g., .highlight), which are more specific than type selectors (e.g., p).
• Source Order: When two rules have the same specificity, the one that appears later in the CSS file will take precedence. This is known as the "source order."
• Importance: You can use the !important declaration to override any other rules, regardless of specificity or source order. However, this should be used sparingly as it can make the CSS harder to maintain.