<div class="arrow"></div>
.arrow {
     position:relative;
     height:16px;
     width:16px;
     background-color:#d01137;
}
 
.arrow::before {
     position:absolute;
     content:"";
     border:solid 16px transparent;
     border-left:solid 16px #d01137;
     top:-8px;
     left:12px;
}

External CSS

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External JavaScript

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