.btn {
	display: inline-block;
	font-weight: 400;
	text-align: center;
	white-space: nowrap;
	vertical-align: middle;
	-webkit-user-select: none;
	-moz-user-select: none;
	-ms-user-select: none;
	user-select: none;
	border: 1px solid transparent;
	padding: .375rem .75rem;
	font-size: 1rem;
	line-height: 1.5;
	border-radius: .25rem;
	transition: color .15s ease-in-out,background-color .15s ease-in-out,border-color .15s ease-in-out,box-shadow .15s ease-in-out;
}

.btn1{
    width: 40px;
    height: 40px;
    font-size:1.5rem;
    margin:0;
    margin-left: 5px;
    margin-right: 5px;
    padding: inherit;
    background-color: cornflowerblue;
    text-align: center;
}

.btn2{
    height: 40px;
}

.z4{
    z-index: 4;
}

.z1{
    z-index: 1;
}