如何在悬停时使内部阴影透明

Question

我想制作悬停时出现的黑色环是透明的.但是当我改变box-shadow: 0 0 0 5px #000, 0 0 0 10px green到 box-shadow: 0 0 0 5px transparent, 0 0 0 10px green它没有出现.我该如何实现呢？

html { 
  background-image: url('https://cdn-images-1.medium.com/max/800/1*aoR-yl7jicuEvQ5hZoQvjw.png');
  background-size: 100%;
}
div{
  position: relative;
  width: 150px;
  height: 150px;
  background: #ccc;
  border-radius: 50%;
  transition: 0.3s;
  border: 5px solid #fff;
}
div:hover{
  box-shadow: 0 0 0 5px #000, 0 0 0 10px green;
}

<div></div>

Answer 1

我不认为你可以用这种方式做到这一点，但是是的，可以通过使用伪元素

例如

div:after {
  content: "";
  bottom: -10px;
  top: -10px;
  left: -10px;
  right: -10px;
  border-radius: 50%;
  position: absolute;
  transition: all 0.3s;
}

div:hover:after {
  box-shadow: 0 0 0 5px green;
}

div:after {
  content: "";
  bottom: -10px;
  top: -10px;
  left: -10px;
  right: -10px;
  border-radius: 50%;
  position: absolute;
  transition: all 0.3s;
}

div:hover:after {
  box-shadow: 0 0 0 5px green;
}

html {
  background-image: url('https://cdn-images-1.medium.com/max/800/1*aoR-yl7jicuEvQ5hZoQvjw.png');
  background-size: 100%;
}

div {
  position: relative;
  width: 150px;
  height: 150px;
  background: #ccc;
  border-radius: 50%;
  transition: 0.3s;
  border: 5px solid #fff;
}

div:after {
  content: "";
  bottom: -10px;
  top: -10px;
  left: -10px;
  right: -10px;
  border-radius: 50%;
  position: absolute;
  transition: all 0.3s;
}

div:hover:after {
  box-shadow: 0 0 0 5px green;
}