意想不到的 CSS 伪元素 before/after 各种骚操作

Question

CSS 伪元素 before/after 我们经常用到，常见的就是画个三角形、绘画背景阴影等，这篇文章将给大家分享还有很多有趣的操作，比如画线画图标等。

画细线

普通的 border 最小高度为1px，用伪元素+transform 属性可以画出小于 1px 的细线

.thin-line {
  height: 40px;
  line-height: 40px;
  position: relative;
  border-top: 1px solid #ff4891;
}

.thin-line:after {
  content: "";
  height: 1px;
  position: absolute;
  left: 0;
  bottom: 0;
  right: 0;
  top: auto;
  background-color: #ff4891;
  display: block;
  -webkit-transform-origin: 100% 0;
  transform-origin: 100% 0;
  -webkit-transform: scaleY(0.3);
  transform: scaleY(0.3);
}

<div class="thin-line">上为1px的线，下为利用伪元素绘制的0.3px的细线</div>

效果如下：

在线示例：https://www.wenjiangs.com/runcode?slug=UOa00p

画图形

.mt-20 {
  margin-top: 20px;
}

.title {
  padding: 0 30px;
  position: relative;
}

.circle:before {
  content: "";
  width: 12px;
  height: 12px;
  display: block;
  border-radius: 50%;
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  background-color: #ff4891;
}

.rhombus:before {
  content: "";
  width: 10px;
  height: 10px;
  display: block;
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%) rotate(45deg);
  background-color: #ff4891;
}

.triangle:before {
  content: "";
  width: 0;
  height: 0;
  display: block;
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  border-left: 10px solid #ff4891;
  border-top: 10px solid transparent;
  border-right: none;
  border-bottom: 10px solid transparent;
}

.parallelogram:before {
  content: "";
  width: 12px;
  height: 10px;
  display: block;
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%) skew(-30deg);
  background-color: #ff4891;
}

.isoscelesTrapezoid:before {
  content: "";
  width: 12px;
  height: 10px;
  display: block;
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%) perspective(1px) rotateX(3deg);
  background-color: #ff4891;
}

.star-six:before {
  content: "";
  width: 0;
  height: 0;
  border-left: 8px solid transparent;
  border-right: 8px solid transparent;
  border-bottom: 16px solid #ff4891;
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
}

.star-six:after {
  width: 0;
  height: 0;
  border-left: 8px solid transparent;
  border-right: 8px solid transparent;
  border-top: 16px solid #ff4891;
  content: "";
  position: absolute;
  left: 0;
  top: calc(50% + 6px);
  transform: translateY(-50%);
}

.arrow-right:after {
  content: "";
  display: inline-block;
  height: 10px;
  width: 10px;
  border-width: 2px 2px 0 0;
  border-color: #ff4891;
  border-style: solid;
  transform: matrix(0.71, 0.71, -0.71, 0.71, 0, 0) translateY(-50%);
  position: absolute;
  top: 50%;
  left: 0;
}

<div class="title rhombus mt-20">菱形</div>
<div class="title circle mt-20">圆形</div>
<div class="title triangle mt-20">三角形</div>
<div class="title parallelogram mt-20">平行四边形</div>
<div class="title isoscelesTrapezoid mt-20">等腰梯形</div>
<div class="title star-six mt-20">六角星</div>

效果如下：

在线示例：https://www.wenjiangs.com/runcode?slug=WRS3Gkcn

特殊字符

.book,
.step {
  display: inline-block;
  position: relative;
}

.book::before {
  content: "《";
  left: -10px;
}

.book::after {
  content: "》";
  right: -10px;
}

.step::before {
  content: "1";
  left: 0;
  width: 20px;
  height: 20px;
  line-height: 20px;
  border-radius: 50%;
  display: inline-block;
  background: #000;
  color: #ffffff;
  text-align: center;
  margin-right: 8px;
}

.sun::before {
  content: "\2600";
  font-size: 16px;
}
.phoneNumber::before {
  content: "\260E";
  font-size: 16px;
}

<div class="book mt-20">大秦帝国</div>
<br />
<div class="step mt-20">步骤一</div>
<br />
<div class="sun mt-20">太阳</div>
<div class="phoneNumber mt-20">18945645654</div>

效果如下：

在线示例：https://www.wenjiangs.com/runcode?slug=D5pzP65d

附：HTML CSS 特殊字符表

画图标

有大神用伪元素创建了84种小图标，具体可查看：http://nicolasgallagher.com/pure-css-gui-icons/