How to use CSS to animate the border of an element

How to use CSS to realize the border animation effect of elements

Introduction:
In web design, in order to increase the user’s visual experience and the attractiveness of the page, it is often Some animation effects will be used to make page elements more vivid and interesting. Among them, border animation is a very common effect, which can make the element border change, flicker or flow dynamically. This article will introduce how to use CSS to animate the border of elements and provide specific code examples.

1. Realize the border color change animation
To realize the border color change animation effect, you can use the @keyframes rule and animation attribute of CSS. The following is a simple sample code:

HTML code:

<div class="box"></div>

CSS code:

.box {
  width: 200px;
  height: 200px;
  border: 2px solid #000;
  animation: colorChange 3s infinite;
}

@keyframes colorChange {
  0% {
    border-color: red;
  }
  50% {
    border-color: blue;
  }
  100% {
    border-color: green;
  }
}

In the above code, the change process of border color is described by defining @keyframes rules . During the animation process from 0% to 50%, the border color gradually transitions from red to blue; during the animation process from 50% to 100%, the border color gradually transitions from blue to green. Apply the animation to the .box element through the animation attribute.

2. Implement border flashing animation
To achieve border flashing animation effect, you can also use CSS @keyframes rules and animation attributes. The following is a simple sample code:

HTML code:

<div class="box"></div>

CSS code:

.box {
  width: 200px;
  height: 200px;
  border: 2px solid #000;
  animation: blinking 1s infinite;
}

@keyframes blinking {
  0% {
    border-color: transparent;
  }
  50% {
    border-color: red;
  }
  100% {
    border-color: transparent;
  }
}

In the above code, the change process of border color is described by defining @keyframes rules . During the animation process from 0% to 50%, the border color is transparent, showing a flickering effect; during the animation process from 50% to 100%, the border color becomes transparent again, giving the border a flickering effect. Apply the animation to the .box element through the animation attribute.

3. Implement border flow animation
To achieve border flow animation effect, you can use CSS @keyframes rules and animation attributes, as well as auxiliary pseudo-elements. The following is a simple sample code:

HTML code:

<div class="box"></div>

CSS code:

.box {
  width: 200px;
  height: 200px;
  position: relative;
}

.box:before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 2px solid red;
  animation: flowing 2s infinite;
}

@keyframes flowing {
  0% {
    border-width: 0;
  }
  50% {
    border-width: 4px;
  }
  100% {
    border-width: 0;
  }
}

In the above code, by adding the :before pseudo-element to the .box element, and Set the width and height of the pseudo element to be the same as the .box element, and set the border color of the pseudo element to red. Describe the changing process of border width by defining @keyframes rules. During the animation process from 0% to 50%, the border width gradually increases from 0 to 4px; during the animation process from 50% to 100%, the border width becomes 0 again, thereby achieving a flowing border effect. Apply the animation to the pseudo element through the animation attribute.

Summary:
This article introduces how to use CSS to achieve the border animation effect of elements, and provides specific code examples. Through the reasonable use of @keyframes rules and animation attributes, we can achieve different animation effects such as color changes, flickering and flow of borders, adding more creativity and charm to web design. I hope this article is helpful to you, thank you for reading!

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