<div class="top"></div>
<div class="mid"></div>
<div class="bot"></div>
<div class="line"></div>
<style>
body {background: #5DBCF9; margin: 0}
.top, .bot {height: 2.5rem; width: 7.5rem}
.top {border-bottom: 2.5rem #FFF solid}
.bot {border-top: 2.5rem #FFF solid}
.mid {
width: 11.25rem;
height: 7.5rem;
margin: 0.625rem 0;
border-right: 2.5rem #FFF solid;
}
.line {
position: absolute;
height: 100%;
width: 2.5rem;
background: #FFF;
top: 0;
left: 2.5rem;
}
</style>