Discuss the differences between CSS3 and previous versions

CSS3 is an upgraded version of CSS technology. Compared with its previous version, it adds many new functions and features. In this article, we will explore the differences between CSS3 and its predecessors.

1. Selectors

The selectors in CSS3 are more flexible than previous versions. In addition to the previous Id, class, and tag selectors, CSS3 also introduced attribute selectors, pseudo-class selectors, and pseudo-element selectors.

Attribute selectors can match styles based on the attributes of elements. For example, [type="text"] can select all elements whose type attribute value is text.

Pseudo-class selectors can match styles based on specific states or positions. For example: hover can match elements in the mouse hover state.

Pseudo-element selectors are used to add styles to specific parts of a selector. For example::before can add a pseudo element in front of the selector.

2. Border

The border in CSS3 is more powerful than previous versions. In previous versions, we could only set simple solid borders for elements, but in CSS3, border styles can be dashed, dotted, or double.

In addition, CSS3 also supports setting different styles for a certain border, such as adding styles only to the top border.

3. Box Model

In the CSS3 specification, a new box model-box-sizing attribute is introduced.

In CSS2.1, the width and height in the box model only include the internal width and height of the element, while in CSS3, the width of the box model includes the border and padding of the element. (padding) and content area (content).

If the box-sizing property is set to border-box, the width of the element includes the border and padding, and the width of the content area will be automatically adjusted to fit.

4. Gradient

In CSS3, we can add a more vivid effect to elements by adding a gradient background. CSS3 supports linear gradients and radial gradients.

Linear gradient can achieve a smooth transition of colors in one direction, while radial gradient gradually fades the color with a point as the center.

5. Animation and Transition

One of the most popular features in CSS3 is support for animation and transition. In CSS3, we can set animation effects for elements, such as rotation, fade in and out, etc., and we can also use transitions to achieve smooth color transitions or size changes.

6. Font

In CSS3, we can use the @font-face rule to use custom fonts. This way, even if the user doesn't have the required font installed, we can use it in the web page.

In addition, CSS3 also supports the font-size-adjust attribute, which allows us to achieve a more consistent font size effect on different browsers and devices.

Summary:

Compared with previous versions, CSS3 has more flexible and powerful selectors and border styles, supports new box models and gradient effects, and also adds animations and transitions. Functions such as effects and custom fonts make front-end development more efficient, easy to operate and of high quality.

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