Css Arrow with Drop Shadow

HTML

<div id="nicebox" class="arrow_box">
		<a href="logout.php"></a>

		
    </div>

CSS

.arrow_box {
        top:40px;
        position: relative;
        background: #ffffff;
        border: 1px solid #719ECE;
        width: 200px;
        height: 200px;
        border-radius: 3px;
        -webkit-filter: drop-shadow(0 1px 10px rgba(113,158,206,0.8));
    }
    .arrow_box:after, 
    .arrow_box:before {
        bottom: 100%;
        border: solid transparent;
        content: " ";
        height: 0;
        width: 0;
        position: absolute;
        pointer-events: none;
    }
    
    .arrow_box:after {
        border-color: rgba(255, 255, 255, 0);
        border-bottom-color: #ffffff;
        border-width: 19px;
        left: 70%;
        margin-left: -19px;
    }
    .arrow_box:before {
        border-color: rgba(113, 158, 206, 0);
        border-bottom-color: #719ECE;
        border-width: 20px;
        left: 70%;
        margin-left: -20px;
    }