CSS: Вертикальный таймлайн

Рассмотрим один из вариантов стилизации вертикального таймлайна как показано на картинке. Он является адаптивным, на мобильных устройствах элементы выстраиваются в одну колонку.

HTML код:

<div class="timeline">
		<div class="item">
			<div class="icon">1</div>
			<div class="content">
				<h4>Lorem ipsum dolor sit amet consectetur adipisicing elit.</h4>
				<p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Vitae at rerum ut amet blanditiis. Deserunt quisquam veritatis amet natus sint. Ab facilis ex recusandae earum magnam sapiente dicta, modi deserunt?</p>
			</div>
		</div>
		<div class="item">
			<div class="icon">2</div>
			<div class="content">
				<h4>Lorem ipsum dolor sit amet consectetur adipisicing elit.</h4>
				<p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Vitae at rerum ut amet blanditiis. Deserunt quisquam veritatis amet natus sint. Ab facilis ex recusandae earum magnam sapiente dicta, modi deserunt?</p>
			</div>
		</div>
		<div class="item">
			<div class="icon">3</div>
			<div class="content">
				<h4>Lorem ipsum dolor sit amet consectetur adipisicing elit.</h4>
				<p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Vitae at rerum ut amet blanditiis. Deserunt quisquam veritatis amet natus sint. Ab facilis ex recusandae earum magnam sapiente dicta, modi deserunt?</p>
			</div>
		</div>
	</div>

CSS код:

*{
	font-family: Arial, Helvetica, sans-serif;
}

.timeline *, 
.timeline *:before, 
.timeline *:after {
	box-sizing: border-box;
}

.timeline {
	max-width: 1000px;
	width: 96%;
	margin: 30px auto;
	position: relative;
	padding: 0 10px;
}

.timeline:before {
	content: "";
	width: 3px;
	height: 100%;
	background: #737575;
	left: 50%;
	top: 0;
	position: absolute;
}

.timeline:after {	
	content: "";
	clear: both;
	display: table;
	width: 100%;
}

.timeline .item {
	margin-bottom: 20px;
	position: relative;
}

.timeline .item:after, 
.timeline .item:before {
	content: '';
	display: block;
	width: 100%;
	clear: both;
}

.timeline .item .icon {
	background: #737575;
	color: #FFF;
	text-align: center;
	font-size: 24px;
	line-height: 50px;
	width: 50px;
	height: 50px;
	position: absolute;
	top: 0;
	left: 50%;
	overflow: hidden;
	margin-left: -23px;
	border-radius: 50%;
}

.timeline .item .content {
	width: 45%;
	background: #fff;
	padding: 20px;
	box-shadow: 0 2px 5px rgba(0,0,0,0.2), 0 4px 10px rgba(0,0,0,0.2);
	border-radius: 3px;
}
.timeline .item .content h4 {
	padding: 15px;
	background: #737575;
	color: #fff;
	margin: -20px -20px 0px -20px;
	font-weight: 300;
	border-radius: 3px 3px 0px 0px;
}
.timeline .item .content:before {
	content: '';
	position: absolute;
	left: 45%;
	top: 20px;
	width: 0;
	height: 0;
	border-top: 7px solid transparent;
	border-bottom: 7px solid transparent;
	border-left: 7px solid #737575;
}
.timeline .item:nth-child(even) .content {
	float: right;
}
.timeline .item:nth-child(even) .content:before {
	content: '';
	right: 45%;
	left: inherit;
	border-left: 0;
	border-right: 7px solid #737575;
}
@media screen and (max-width: 768px) {
	.timeline {
		margin: 30px;
		padding: 0px;
		width: 90%;
	}
	.timeline:before {
		left: 0;
	}
	.timeline .item .content {
		width: 90%;
		float: right;
	}
	.timeline .item .content:before, 
	.timeline .item:nth-child(even) .content:before {
		left: 10%;
		margin-left: -6px;
		border-left: 0;
		border-right: 7px solid #737575;
	}
	.timeline .item .icon {
		left: 0;
	}
}

Получим следующий результат:

<style>
*{
	font-family: Arial, Helvetica, sans-serif;
}

.timeline *, 
.timeline *:before, 
.timeline *:after {
	box-sizing: border-box;
}

.timeline {
	max-width: 1000px;
	width: 96%;
	margin: 30px auto;
	position: relative;
	padding: 0 10px;
}

.timeline:before {
	content: "";
	width: 3px;
	height: 100%;
	background: #737575;
	left: 50%;
	top: 0;
	position: absolute;
}

.timeline:after {	
	content: "";
	clear: both;
	display: table;
	width: 100%;
}

.timeline .item {
	margin-bottom: 20px;
	position: relative;
}

.timeline .item:after, 
.timeline .item:before {
	content: '';
	display: block;
	width: 100%;
	clear: both;
}

.timeline .item .icon {
	background: #737575;
	color: #FFF;
	text-align: center;
	font-size: 24px;
	line-height: 50px;
	width: 50px;
	height: 50px;
	position: absolute;
	top: 0;
	left: 50%;
	overflow: hidden;
	margin-left: -23px;
	border-radius: 50%;
}

.timeline .item .content {
	width: 45%;
	background: #fff;
	padding: 20px;
	box-shadow: 0 2px 5px rgba(0,0,0,0.2), 0 4px 10px rgba(0,0,0,0.2);
	border-radius: 3px;
}
.timeline .item .content h4 {
	padding: 15px;
	background: #737575;
	color: #fff;
	margin: -20px -20px 0px -20px;
	font-weight: 300;
	border-radius: 3px 3px 0px 0px;
}
.timeline .item .content:before {
	content: '';
	position: absolute;
	left: 45%;
	top: 20px;
	width: 0;
	height: 0;
	border-top: 7px solid transparent;
	border-bottom: 7px solid transparent;
	border-left: 7px solid #737575;
}
.timeline .item:nth-child(even) .content {
	float: right;
}
.timeline .item:nth-child(even) .content:before {
	content: '';
	right: 45%;
	left: inherit;
	border-left: 0;
	border-right: 7px solid #737575;
}
@media screen and (max-width: 768px) {
	.timeline {
		margin: 30px;
		padding: 0px;
		width: 90%;
	}
	.timeline:before {
		left: 0;
	}
	.timeline .item .content {
		width: 90%;
		float: right;
	}
	.timeline .item .content:before, 
	.timeline .item:nth-child(even) .content:before {
		left: 10%;
		margin-left: -6px;
		border-left: 0;
		border-right: 7px solid #737575;
	}
	.timeline .item .icon {
		left: 0;
	}
}
</style>

<div class="timeline">
		<div class="item">
			<div class="icon">1</div>
			<div class="content">
				<h4>Lorem ipsum dolor sit amet consectetur adipisicing elit.</h4>
				<p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Vitae at rerum ut amet blanditiis. Deserunt quisquam veritatis amet natus sint. Ab facilis ex recusandae earum magnam sapiente dicta, modi deserunt?</p>
			</div>
		</div>
		<div class="item">
			<div class="icon">2</div>
			<div class="content">
				<h4>Lorem ipsum dolor sit amet consectetur adipisicing elit.</h4>
				<p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Vitae at rerum ut amet blanditiis. Deserunt quisquam veritatis amet natus sint. Ab facilis ex recusandae earum magnam sapiente dicta, modi deserunt?</p>
			</div>
		</div>
		<div class="item">
			<div class="icon">3</div>
			<div class="content">
				<h4>Lorem ipsum dolor sit amet consectetur adipisicing elit.</h4>
				<p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Vitae at rerum ut amet blanditiis. Deserunt quisquam veritatis amet natus sint. Ab facilis ex recusandae earum magnam sapiente dicta, modi deserunt?</p>
			</div>
		</div>
	</div>