<html>
<head>
    <style>
        div {
            width: 200px;
            height: 200px;
            float: left;
        }
        /*tweak this until it's actually right... */
        #topleft {
            width: 0; 
            height: 0; 
            border-left: 100px solid rgb(64,64,64);
            border-top: 100px solid rgb(32,32,32);
        }
        #topright {
            width: 0; 
            height: 0; 
            border-right: 100px solid rgb(224,224,224);
            border-top: 100px solid rgb(255,255,255);
        }
        #bottomleft {
            clear: left;
            width: 0; 
            height: 0; 
            border-left: 100px solid rgb(96,96,96);
            border-bottom: 100px solid rgb(128,128,128);
        }
        #bottomright {
            width: 0; 
            height: 0; 
            border-right: 100px solid rgb(192,192,192);
            border-bottom: 100px solid rgb(160,160,160);
        }
        .box {
            position: absolute;
        }
        .x {
            position: absolute;
            -webkit-clip-path: polygon(0% 0%, 0% 10%, 40% 50%, 0% 90%, 0% 100%, 10% 100%, 50% 60%, 90% 100%, 100% 100%, 100% 90%, 60% 50%, 100% 10%, 100% 0%, 90% 0%, 50% 40%, 10% 0%);
        }
        #x {
            background-color:white;
        }
        .plus {
            position: absolute;
            -webkit-clip-path: polygon(45% 0%, 55% 0%, 55% 45%, 100% 45%, 100% 55%, 55% 55%, 55% 100%, 45% 100%, 45% 55%, 0% 55%, 0% 45%, 45% 45%);
        }
        #plus {
            background-color:white;
        }
        
    </style>
</head>
<body>
    <div>
        <div class="box">
            <div id="topleft"></div>
            <div id="topright"></div>
            <div id="bottomleft"></div>
            <div id="bottomright"></div>
        </div>
        <div id="x" class="x"></div>
        <div id="plus" class="plus"></div>
    </div>
</body>
</html>