效果
.left-top,.right-top,.left-bottom,.right-bottom{
position:absolute;
width:13px;
height:13px;
}
.left-top{
left:0;
top:0;
border-left:solid 2px #045291;
border-top:solid 2px #045291;
}
.right-top{
right:0;
top:0;
border-right:solid 2px #045291;
border-top:solid 2px #045291;
}
.left-bottom{
left:0;
bottom:0;
border-left:solid 2px #045291;
border-bottom:solid 2px #045291;
}
.right-bottom{
right:0;
bottom:0;
border-right:solid 2px #045291;
border-bottom:solid 2px #045291;
}
<div class="count-resource ">
<div class="com-count-title">企业总量统计</div>
<div class="com-screen-content2">
<ul class="use-data">
<li>
<p class="data-count">15681 </p>
<span class="data-name">企业总量</span>
</li>
<li>
<p class="data-count"> 5731</p>
<span class="data-name">平台注册量</span>
</li>
<li>
<p class="data-count">1000</p>
<span class="data-name">更新量</span>
</li>
</ul>
<div class="com-screen-content">
<div id="main2" style="margin-top:10px;width:100%;height:240px;"></div>
</div>
<span class="left-top"></span>
<span class="right-top"></span>
<span class="left-bottom"></span>
<span class="right-bottom"></span>
</div>
</div>