JSFiddle - React, Tailwind, and code Playground

HTML

<div>Hello!</div>
<div class="b">Hello, world!</div>
<div>A hella lot of lorem ipsum</div>

CSS

body { background:url('http://i.imgur.com/VEXWZ.png') no-repeat; padding:20px; }
div {
    height: 20px;
    padding:2px 5px 0 5px;
    color:white;
    background: rgba(0,0,0,.5);
    margin: 0 10px;
    position: relative;
    border-top-left-radius: 6px 4px;
    border-top-right-radius: 6px 4px;
    font-family:sans-serif;
    font-size:13px;
    line-height:20px;
    vertical-align:bottom;
    display:inline-block;
    white-space:nowrap;
}

div:before {
    content: '';
    line-height: 0;
    font-size: 0;
    width: 0;
    height: 0;
    border-bottom: 19px solid rgba(0,0,0,.5);
    border-left: 9px solid transparent;
    position: absolute;
    bottom: 0;
    left: -9px;
}

div:after {
    content: '';
    line-height: 0;
    font-size: 0;
    width: 0;
    height: 0;
    border-bottom: 19px solid rgba(0,0,0,.5);
    border-right: 9px solid transparent;
    position: absolute;
    bottom: 0;
    right: -9px;
}

.b { background:black; margin:0 -7px 0 20px; } 
.b:after, .b:before { border-bottom-color:black; }