Border-bottom Почему в виде трапеции?

#travel_guide{
	font-size: 17px; 
	font-family: "PTSans Bold";
	color: rgb(112, 112, 112);
	border-left: 1px solid white;
	border-right: 1px solid white;
	border-top: 1px solid white;
	border-bottom: 4px solid #6017a3;
	box-shadow: -1px 1px 8px rgb(0, 0, 0, 0.10);
	background-color: white;
	transform: translate(0px, -157px);
	width: 90px;
	padding-left: 45px;
	padding-right: 32px;
	padding-top: 60px;
	padding-bottom: 35px
}

#travel_guide:hover{
	border-bottom: 12px solid #701dbb;
	transform: translate(0px, -169px);
}