css 两边是线，中间文字的多种实现方法

<div class="soild_text_one">
	  <fieldset>
	    	<legend>历史活动一</legend>
	  </fieldset>
</div> 

<div class="soild_text_two">
  	<hr/><span>历史活动二</span><hr/>
</div>

<div class="soild_text_three">
  	 历史活动三
</div>

.soild_text_one{
  width:500px;
  margin:0 auto;
  fieldset{
       height: 500px;
       border-left: none;
       border-right: none;
       border-bottom: none;
       color: #009688;
       border-color: #defffc;
       height:20px;
       legend{
           text-align: center;
           padding: 0 10px;
           font-size: 14px;
       }
   }
}

.soild_text_two{
  text-align:center;
  width:500px;
  margin:0 auto;
  height:20px;
  font-size: 14px;
  color: #4caf50;
  hr{
    width:200px;
    display:inline-block;
    vertical-align:middle;
    border-color: #e4ffe6;
  }
  span{
    padding: 0 10px;
  }
}

.soild_text_three{
  position:relative;
  text-align:center;
  width:500px;
  margin:20px auto;
  height:20px;
  font-size: 14px;
  color:#ff9800;
  &::before,&::after{
    content:"";
    position:absolute;
    top:50%;
    border:solid 1px #fbdfb6;
    width:40%;
  }
  &::before{
    left:0;
  }
  &::after{
    right:0;
  }
}