将 box-shadow 添加到 :after 伪元素

Question

我有一个名为 .testimonial-inner 的 div 并使用 :after 伪元素我有一个位于它下方的箭头指向下方。我遇到的问题是给它添加了一个盒子阴影，所以它们看起来都像是一个自然元素。

三角形上没有box-shadow：

body {
  background: #eee
}
.testimonial-inner {
  background: #fff;
  -webkit-border-radius: 3px;
  -moz-border-radius: 3px;
  border-radius: 3px;
  padding: 30px;
  display: block;
  margin-bottom: 25px;
  position: relative;
  -webkit-box-shadow: 0px 0px 5px 0px rgba(0, 0, 0, 0.25);
  -moz-box-shadow: 0px 0px 5px 0px rgba(0, 0, 0, 0.25);
  box-shadow: 0px 0px 5px 0px rgba(0, 0, 0, 0.75);
}
.testimonial-inner:after {
  top: 100%;
  left: 48px;
  border: solid transparent;
  content: " ";
  height: 0;
  width: 0;
  position: absolute;
  pointer-events: none;
  border-color: rgba(255, 255, 255, 0);
  border-top-color: #fff;
  border-width: 18px;
  margin-left: -18px;
}

<div class="c-4 testimonial-wrap">
  <div class="testimonial-inner">
    <p>Using Facebook was unquestionably the best decision I could possibly have made at the point in my journalistic journey. It enabled me to share my fears, frustrations as well as successes.</p>
  </div>
</div>

注意盒子阴影当前没有环绕箭头。

当我将它添加到 :after 声明时，我得到以下结果：

body {
  background: #eee
}
.testimonial-inner {
  background: #fff;
  -webkit-border-radius: 3px;
  -moz-border-radius: 3px;
  border-radius: 3px;
  padding: 30px;
  display: block;
  margin-bottom: 25px;
  position: relative;
  -webkit-box-shadow: 0px 0px 5px 0px rgba(0, 0, 0, 0.25);
  -moz-box-shadow: 0px 0px 5px 0px rgba(0, 0, 0, 0.25);
  box-shadow: 0px 0px 5px 0px rgba(0, 0, 0, 0.75);
}
.testimonial-inner:after {
  top: 100%;
  left: 48px;
  border: solid transparent;
  content: " ";
  height: 0;
  width: 0;
  position: absolute;
  pointer-events: none;
  border-color: rgba(255, 255, 255, 0);
  border-top-color: #fff;
  border-width: 18px;
  margin-left: -18px;
  -webkit-box-shadow: 0px 0px 5px 0px rgba(0, 0, 0, 0.25);
  -moz-box-shadow: 0px 0px 5px 0px rgba(0, 0, 0, 0.25);
  box-shadow: 0px 0px 5px 0px rgba(0, 0, 0, 0.75);
}

<div class="c-4 testimonial-wrap">
  <div class="testimonial-inner">
    <p>Using Facebook was unquestionably the best decision I could possibly have made at the point in my journalistic journey. It enabled me to share my fears, frustrations as well as successes.</p>
  </div>
</div>

Answer 1

您可以添加另一个 :pseudo-element，将其旋转 45deg 并添加 box-shadow。

Updated Fiddle

body {
  background: #eee
}
.testimonial-inner {
  background: #fff;
  -webkit-border-radius: 3px;
  -moz-border-radius: 3px;
  border-radius: 3px;
  padding: 30px;
  display: block;
  margin-bottom: 25px;
  position: relative;
  box-shadow: 0px 0px 5px 0px rgba(0, 0, 0, 0.75);
}
.testimonial-inner:after {
  top: 100%;
  left: 48px;
  border: solid transparent;
  content: " ";
  height: 0;
  width: 0;
  position: absolute;
  pointer-events: none;
  border-color: rgba(255, 255, 255, 0);
  border-top-color: #fff;
  border-width: 18px;
  margin-left: -18px;
}
.testimonial-inner:before {
  content: '';
  position: absolute;
  transform: rotate(45deg);
  width: 36px;
  height: 36px;
  bottom: -12px;
  z-index: -1;
  box-shadow: 0px 0px 5px 0px rgba(0, 0, 0, 0.75);
}

<div class="c-4 testimonial-wrap">
  <div class="testimonial-inner">
    <p>Using Facebook was unquestionably the best decision I could possibly have made at the point in my journalistic journey. It enabled me to share my fears, frustrations as well as successes.</p>
  </div>
</div>

---

使用svg 作为三角形的另一种方法。

body {
  background: #eee
}
.testimonial-wrap {
  position: relative;
}
.testimonial-inner {
  background: #fff;
  -webkit-border-radius: 3px;
  -moz-border-radius: 3px;
  border-radius: 3px;
  padding: 30px;
  display: block;
  margin-bottom: 25px;
  position: relative;
  box-shadow: 0px 0px 5px 0px rgba(0, 0, 0, 0.75);
}
#triangle {
  position: absolute;
  top: 100%;
  margin-top: -1px;
  left: 50px;
}

<div class="c-4 testimonial-wrap">
  <div class="testimonial-inner">
    <p>Using Facebook was unquestionably the best decision I could possibly have made at the point in my journalistic journey. It enabled me to share my fears, frustrations as well as successes.</p>
  </div>
  <svg id="triangle" width="40" height="26">
    <defs>
      <filter id="f" width="150%" height="130%">
        <feGaussianBlur in="SourceAlpha" stdDeviation="2.5" />
        <feComponentTransfer>
          <feFuncA type="linear" slope="0.8" />
        </feComponentTransfer>
        <feMerge>
          <feMergeNode/>
          <feMergeNode in="SourceGraphic" />
        </feMerge>
      </filter>
    </defs>
    <path filter="url(#f)" d="M0,0 h40 l-20,20z" fill="white" />
  </svg>
</div>

Answer 2

你不能使用 box-shadow 来做你想做的事情。这是因为“箭头”效果是通过在除顶部之外的任何地方使用透明颜色来创建的。这意味着该元素仍然是一个正方形，并且您的阴影将相应地在它周围渲染。

如果您想为图像的形状添加阴影，请尝试使用 SVG，或者仅使用带有预渲染阴影的图像。

<polygon points="220, 150 350, 220" style="fill:#FFFFFF; stroke:#000000;stroke-width:1"/>

Answer 3

恕我直言，我认为这有点骇人听闻，但使用纯 css 来做到这一点：

div{
  height:200px;
  width:100%;
  border-radius:10px;
  background:gray; 
  position:relative;
  box-shadow:0 0px 10px black;
  border:1px solid black;
}


div:before{
  position:absolute;
  bottom:-10px;
  left:40px;
  content:"";
  background:gray;
  height:20px;
  width:20px;
  transform: rotate(45deg);
  border-bottom:1px solid black;
  border-right:1px solid black;
  
  box-shadow:0 0px 10px black;
  }

div:after{
  position:absolute;
  bottom:0px;
  left:30px;
  content:"";
  background:gray;
  height:20px;
  width:40px;

  }

<div>test</div>

Answer 4

过滤器将起作用：

.shadowed {
    -webkit-filter: drop-shadow(0px 2px 2px rgba(130,130,130,1));
    filter        : drop-shadow(0px 2px 2px rgba(130,130,130,1));
    -ms-filter    : "progid:DXImageTransform.Microsoft.Dropshadow(OffX=0, OffY=2, Color='#444')";
    filter        : "progid:DXImageTransform.Microsoft.Dropshadow(OffX=0, OffY=2, Color='#444')";
}

工作示例：http://codepen.io/tolmark12/pen/JopNeR?editors=110

了解更多信息：Creating a true cross browser drop shadow