用纯CSS实现的箭头、css3三角形

 

<hr>





<div id="demo11"></div>

<style>
#demo11 {
  border: 10px solid #000;
  border-left-color: #f00;
  width: 10px;
  height: 10px;
}
</style>
<hr>


<div id="demo12"></div>

<style>
#demo12 {
  border: 10px solid #000;
  border-left-color: #f00;
  width: 0;
  height: 0;
}
</style>

<hr>

<div id="demo14"></div>

<style>
#demo14 {
  border: 10px solid transparent;
  border-left: 20px solid #f00;
  width: 0;
  height: 0px;
}
</style>




<hr>

<span id="demo15">文字内容</span>

<style>
#demo15{
  position: relative;
}
#demo15:after {
  border: 10px solid transparent;
  border-left: 10px solid #f00;
  width: 0;
  height: 0;
  position: absolute;
  content: ' '
}
</style>

<span id="demo15">文字内容15</span>

<style>
#demo16{
  position: relative;
}
#demo16:after, #demo16:before {
  border: 10px solid transparent;
  border-left: 10px solid #fff;
  width: 0;
  height: 0;
  position: absolute;
  top: 0;
  right: -20px;
  content: ' '
}

#demo16:before {
  border-left-color: #f00;
  right: -21px;
}
</style>



<ul id="demo17">
  <li>文字内容 Tab1</li>
  <li>文字内容 Tab2</li>
  <li>文字内容 Tab3</li>
</ul>

<style>
#demo17{
  font-size: 10px;
  height: 24px;
}

#demo17 li {
  float: left;
  position: relative;
  list-style: none;
  margin: 0 20px 12px -19px;
  border-top: solid 1px #ddd;
  border-bottom: solid 1px #ddd;
  padding-left: 12px;
}

#demo17 li:after, #demo17 li:before {
  border: 10px solid transparent;
  border-left: 10px solid #fff;
  width: 0;
  height: 0;
  position: absolute;
  top: 0;
  right: -18px;
  content: ' '
}

#demo17 li:before {
  border-left-color: #ddd;
  right: -19px;
}
</style>


<hr>

<div id="demo"></div>

<style>
#demo {
  width: 100px;
  height: 100px;
  background-color: #ccc;
  position: relative;
  border: 4px solid #333;
}

#demo:after, #demo:before {
  border: solid transparent;
  content: ' ';
  height: 0;
  left: 100%;
  position: absolute;
  width: 0;
}

#demo:after {
  border-width: 9px;
  border-left-color: #ccc;
  top: 15px;
}

#demo:before {
  border-width: 14px;
  border-left-color: #333;
  top: 10px;
}
</style>