css 设置边框边角

效果

 css:

.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;
}

html

        <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;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>