JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap-theme.min.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<div class="col-md-offset-3 col-md-9">
	<div class="panel panel-default">
		<div class="list-group">
      <div class="triangle"></div>
			<div class="list-group-item left-icon" style="padding: 15px 15px;">
				<div class="list-group-item-heading" style="text-transform: uppercase; font-size: 22px;">ООО LOCKPICK</div>
				<div class="list-group-item-desc">ООО, Казань</div>
				<div class="list-group-item-desc"><a href="#">lockpick.ru</a></div>
			</div>
			<div class="list-group-item" style="padding: 15px 15px;">
				<div class="list-group-item-desc">IT, Разработка ПО</div>
				<div class="list-group-item-text" style="margin: 20px 0 0 0;">
					We are a dedicated team of professional lockpicking experts who
					have over ten years of experience in locksmith field
				</div>
				<div class="list-group-item-text" style="margin: 20px 0 0 0;">
					<div style="padding: 10px 0px; text-transform: uppercase; font-family: 'ElektraProBold'; letter-spacing: 0.6px;">Контактное лицо</div>
					<div>Марина Семипядявская<br /><a href="#">marina_s@lockpick.ru</a><br />225-54-43, +7-987-654-1234</div>
				</div>
			</div>
		</div>
	</div>
</div>

CSS

.panel {
  position: relative;
  margin-left: 50px;
}
.list-group-item {
  position: relative;
  z-index: 2;
}
.triangle {
    position: absolute;
    z-index: 1;
    top: 20px;
    right: 100%;
    overflow: hidden;
    width: 25px;
    height: 25px;
    background: transparent;
    box-shadow: 2px -2px 2px #c9c9c9;
}
.triangle:before {
    content: "";
    position: absolute;
    bottom: 9px;
    left: 9px;
    display: block;
    width: 35px;
    height: 35px;
    transform: rotate(45deg);
    background: #fff;
    box-shadow: 0 0 4px #c9c9c9;
}