框阴影无法正常显示

Question

为什么盒子阴影在这里没有正确显示：

.panel:hover {
  box-shadow: 0px 0px 150px #000000;
  z-index: 2;
  -webkit-transition: all 200ms ease-in;
  -webkit-transform: scale(1.3);
  -ms-transition: all 200ms ease-in;
  -ms-transform: scale(1.3);
  -moz-transition: all 200ms ease-in;
  -moz-transform: scale(1.3);
  transition: all 200ms ease-in;
  transform: scale(1.3);
}

Link to JsFiddle。

在某些方框上，它不会显示在右侧。

Answer 1

如果您希望z-index能够始终如一地运作，则需要设置position: relative。

html,
body {
  height: 100%;
  width: 100%;
  background: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAI0lEQVQIW2NkwAT/GdHE/gP5jMiCYAGQIpggXAAmiCIAEgQAAE4FBbECyZcAAAAASUVORK5CYII=) #222;
}
h1 {
  color: white;
  text-align: center;
}

.container {
  width: 80%;
  height: 80%;
  margin: 0 auto;
  border: red;
  color: white;
}

.panel {
  position: relative;   /* ADD THIS */
  float: left;
  min-width: 30%;
  max-width: 30%;
  min-height: 30%;
  max-height: 30%;
  display: flex; /* testing this for aligning text */
  justify-content: center; /* align horizontal */
  align-items: center; /* align vertical */
  background-color: #FF6961;
  margin: 1%;
  border: white;
  color: #222;
  -webkit-transition: all 200ms ease-in;
  -webkit-transform: scale(1);
  -ms-transition: all 200ms ease-in;
  -ms-transform: scale(1);
  -moz-transition: all 200ms ease-in;
  -moz-transform: scale(1);
  transition: all 200ms ease-in;
  transform: scale(1);
  -index: 1;
}

.panel:hover {
  box-shadow: 0px 0px 150px 0px white;
  z-index: 2;
  -webkit-transform: scale(1.3);
  transform: scale(1.3);
}

span {
  display: inline-block;
  vertical-align: middle;
  line-height: normal;  
}

<h1>
Title Here
</h1>
<div class="container">
<div class="panel">
<span>
  Forums
</span>
</div>
<div class="panel">
<span>
  News
</span>
</div>
<div class="panel">
  Leaderboards
</div>
<div class="panel">
  About
</div>
</div>