styles.css

* {
	font-family: 'Open Sans', sans-serif;
}

#app {
	display: block;
	max-width: 200px;
	margin: 0px auto;
}

#output {
	display: block;
	height: 47px;
	width: 100%;
	padding: 10px 20px;
	background: #777;
	border: 1px solid #777;
	color: #fff;
	font-size: 21px;
	font-weight: 400;
	line-height: 25px;
	box-sizing: border-box;
}

#inputs {

}
.row {
	display: flex;
}
.row button {
	display: block;
	position: relative;
	height: 50px;
	width: 25%;
	padding: 0px;
	background: #fff;
	border: none;
	border-bottom: 1px solid #777;
	border-left: 1px solid #777;
	cursor: pointer;
	outline: none;

	font-size: 18px;
	font-weight: 300;
}

.row:first-of-type button {
	background: #ededed;
}

.row button:last-of-type {
	background: orange;
	border-right: 1px solid #777;

	color: #fff;
}

.row button:hover:after {
	content: '';
	display: block;
	position: absolute;
	height: 100%;
	width: 100%;
	left: 0px;
	top: 0px;
	background: rgba(0, 0, 0, 0.06);
}

.row .double-wide {
	width: 50%;
}