<div class="cp_box">
	表示しておくテキスト
	<input id="cp00" type="checkbox">
	<label for="cp00">続きを読む</label>
	<div class="cp_container">
		続きを読むを押すと表示されるテキスト
	</div>
</div>

.cp_box *, .cp_box *:before, .cp_box *:after {
	-webkit-box-sizing: border-box;
	box-sizing: border-box;
}
.cp_box {
	width: auto;
	margin: 2em auto;
}
.cp_box label {
	font-weight: bold;
	position: relative;
	display: block;
	width: 80%;
	margin: auto;
	padding: 0.3em 1em;
	cursor: pointer;
	transition: all 0.3s;
	text-align: center;
	color: #da3c41;
	border: 2px solid #da3c41;
	border-radius: 3px;
}
.cp_box label:hover {
	transition: all 0.3s;
	color: #ffffff;
	background: #da3c41;
}
.cp_box label::after {
	font-family: 'FontAwesome';
	content: ' \f067';
	color: #da3c41;
}
.cp_box label:hover::after {
	color: #ffffff;
}
.cp_box input:checked ~ label::after {
	font-family: 'FontAwesome';
	content: ' \f068';
	color: #da3c41;
}
.cp_box input:checked ~ label:hover::after {
	color: #ffffff;
}
.cp_box input {
	display: none;
}
.cp_box .cp_container {
	position: relative;
	z-index: 10;
	overflow: hidden;
	height: 0;
	margin-top: -1px;
	transition: height 0.3s ease-in-out,box-shadow 0.6s linear;
	background: rgba(255, 255, 255, 0.5);
}
.cp_box input:checked ~ div {
	transition: height 0.5s ease-in-out,box-shadow 0.1s linear;
}
/* 続きを読むを押すと表示されるテキストの高さ */
.cp_box input:checked ~ div.cp_container {
	height: 300px;
}