Html 将 box-shadow 添加到 :after 伪元素

Adding box-shadow to a :after pseudo element

提问by egr103

I have a div called .testimonial-innerand using the :afterpseudo element I have an arrow that sits underneath it pointing down. The problem I'm having is adding a box-shadow to it all so they both look like one natural element.

我有一个 div 调用.testimonial-inner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一个框阴影，这样它们看起来都像一个自然元素。

Without box-shadowon the triangle:

没有box-shadow在三角形上：

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>

Notice the box shadow currently doesn't wrap around the arrow.

请注意，框阴影当前没有环绕箭头。

When I add it to the :afterdeclaration I get the following result:

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>

回答by tolmark

A filter will work:

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')";
}

Working Example : http://codepen.io/tolmark12/pen/JopNeR?editors=110

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

Learn more at : Creating a true cross browser drop shadow

了解更多信息：创建真正的跨浏览器投影

回答by Weafs.py

You could add another :pseudo-element, rotate it by 45degand add box-shadowto it.

您可以添加另一个：伪元素，将其旋转45deg并添加box-shadow到其中。

Updated Fiddle

更新的小提琴

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>

---

---

Another approach using svgas a triangle.

另一种使用svg三角形的方法。

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>

回答by jbutler483

IMHO, I think it's a bit hackish, but is using pure css to do this:

恕我直言，我认为这有点hackish，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>

回答by flagoworld

You can't do what you want to do here using box-shadow. This is because the "arrow" effect is created by using a transparent color everywhere except the top. This means that the element is still a square and your shadow will render around it accordingly.

你不能在这里使用 box-shadow 做你想做的事。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，您的阴影将相应地围绕它呈现。

If you want to add a shadow to the shape of the image, try using an SVG, or just an image with a pre-rendered shadow.

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"/>