/*脚*/
#bottom_div{
	background: #253E4F;
	color: #f1f1f1;
	/*border: 1px solid red;*/
	text-align: center;
	padding-top: 5px;
	padding-bottom: 5px;
}

@media(max-width: 768px){
	#bottom_div {
	    margin-top: 20px;
	}
	#return_to_top_div {
	    bottom: 0px;
	}
}