/*
   对话气泡
   用法：使用.speech-bubble和.speech-bubble-DIRECTION类
   <div class="speech-bubble speech-bubble-top">Hi there</div>
*/
  
.speech-bubble {
  position: relative;
  background-color: #292929;
  
  /*width: 200px;
  height: 150px;
  line-height: 150px; /* 垂直居中 */
  color: white;
  text-align: center;
  border-radius: 1px;
  font-family: sans-serif;
}
  
.speech-bubble:after {
  content: '';
  position: absolute;
  
  width: 0;
  height: 0;
  
  border: 15px solid;
}
  
/* 箭头的位置 */
.speech-bubble-top:after {
  border-bottom-color: #292929;
  left: 50%;
  bottom: 100%;
  margin-left: -15px;  
}
.speech-bubble-right:after {
  border-left-color: #292929;
  
  left: 100%;
  top: 50%;
  margin-top: -15px;   
}
  
.speech-bubble-bottom:after {
  border-top-color: #292929;
  top: 100%;
  left: 50%;
  margin-left: -15px;  
}
  
.speech-bubble-left:after {
  border-right-color: #292929;
  top: 50%;
  right: 100%;
  margin-top: -15px;   
}