JSFiddle - React, Tailwind, and code Playground

HTML

<div id="f"></div>

CSS

#f {
    width: 100px;
    height: 80px;
    background-color: #3B5998;
    border-bottom: 20px solid #6d84b4;
    position: relative;
}
#f:before {
    position: absolute;
    top: 15px;
    right: 15px;
    border: 15px solid #fff;
    border-bottom: none;
    border-right: none;
    border-top-left-radius: 15px;
    width: 15px;
    height: 65px;
    content: "";
}
#f:after {
    position: absolute;
    top: 44px;
    left: 43px;
    height: 15px;
    width: 42px;
    background-color: #fff;
    content: "";
}