cssboxshadow（cssboxshadow背景图片轮廓）

CSS Box Shadow

Introduction:

CSS Box Shadow is a property that allows developers to add shadows to elements on a webpage. This can be useful for creating depth and dimension, as well as providing visual cues to the user.

I. Syntax:

The syntax for the box shadow property is as follows:

box-shadow: h-offset v-offset blur spread color;

- h-offset: The horizontal offset specifies how far the shadow should be placed to the right or left of the element.

- v-offset: The vertical offset specifies how far the shadow should be placed below or above the element.

- blur: The blur radius controls the blurriness of the shadow. A higher value creates a more blurred effect.

- spread: The spread radius determines the size of the shadow, with a positive value expanding the shadow and a negative value shrinking it.

- color: The color parameter sets the color of the shadow.

II. Applying Box Shadow:

To apply a box shadow to an element, use the box-shadow property in the CSS declaration block. Here's an example:

.box {

box-shadow: 2px 2px 4px rgba(0, 0, 0, 0.4);

In this example, the box shadow has a horizontal offset of 2 pixels, a vertical offset of 2 pixels, a blur radius of 4 pixels, and a color of rgba(0, 0, 0, 0.4).

III. Multiple Shadows:

CSS Box Shadow also allows for multiple shadows to be applied to an element. The box-shadow property can accept multiple values, separated by commas. Here's an example:

.box {

box-shadow: 2px 2px 4px rgba(0, 0, 0, 0.4), -2px -2px 4px rgba(255, 255, 255, 0.4);

In this example, there are two box shadows applied to the element. The first shadow has a positive horizontal and vertical offset, while the second shadow has a negative horizontal and vertical offset. This creates a double-shadow effect.

IV. Box Shadow on Specific Sides:

By using the 4-value syntax for the box-shadow property, it's possible to apply a shadow to specific sides of an element. Here's an example:

.box {

box-shadow: 2px 2px 4px rgba(0, 0, 0, 0.4)

0 10px 0px rgba(0, 0, 0, 0.1)

-2px -2px 4px rgba(255, 255, 255, 0.4);

In this example, the first line of the box-shadow property creates a shadow on all sides, while the second line creates a shadow only on the bottom side.

Conclusion:

CSS Box Shadow is a powerful property that allows developers to add shadows to elements on a webpage. By using different values for the box-shadow property, such as offsets, blur radius, spread radius, and color, it is possible to create a variety of shadow effects that enhance the design and user experience.