<ol class="cp_clist">
	<li>css</li>
	<li>html</li>
	<li>copy</li>
	<li>easy</li>
</ol>

ol.cp_clist {
	counter-reset:cp_clist;
	list-style-type:none;
	padding: 0.5em;
}
ol.cp_clist li {
	position:relative;
	line-height: 30px;
	margin: 7px 0 10px 36px;
	padding-left: 10px;
	background: #F8BBD0;
}
ol.cp_clist li:before {
	position: absolute;
	top: 50%;
	left: -40px;
	/* カウントさせる */
	counter-increment: cp_clist;
	content: counter(cp_clist);
	/*装飾*/
	padding: 0 0.2em 0 0.2em;
	font-weight: bold;
	color: #fff;
	background: #F06292;
	width: 30px;
	height: 30px;
	text-align: center;
	transform: translateY(-50%);
}
ol.cp_clist li:after {
	content:'';
	display: block;
	position: absolute;
	top: 50%;
	left: -10px;
	height: 0;
	width: 0;
	border-top: 4px solid transparent;
	border-bottom: 4px solid transparent;
	border-left: 7px solid #F06292;
	transform: translateY(-50%);
}