30秒学会 CSS 片段 – Button border animation

Creates a border animation on hover.

• Use the :before and :after pseudo-elements as borders that animate on hover.

预览

HTML

<button class="animated-border-button">Submit</button>

CSS

.animated-border-button {
  background-color: #141414;
  border: none;
  color: #ffffff;
  outline: none;
  padding: 12px 40px 10px;
  position: relative;
}

.animated-border-button:before,
.animated-border-button:after {
  border: 0 solid transparent;
  transition: all 0.3s;
  content: '';
  height: 0;
  position: absolute;
  width: 24px;
}

.animated-border-button:before {
  border-top: 2px solid #141414;
  right: 0;
  top: -4px;
}

.animated-border-button:after {
  border-bottom: 2px solid #141414;
  bottom: -4px;
  left: 0;
}

.animated-border-button:hover:before,
.animated-border-button:hover:after {
  width: 100%;
}

翻译自：https://www.30secondsofcode.org/css/s/button-border-animation