style.css

* {
	margin: 0;
	padding: 0;
	box-sizing: border-box;
}

body {
	display: flex;
	justify-content: center;
	align-items: center;
	min-height: 100vh;
	background: #282A36;
}

.navigation {
	position: relative;
	width: 400px;
	height: 60px;
	background: white;
	display: flex;
	justify-content: center;
	align-items: center;
	border-radius: 10px;
}

.navigation ul {
	width: 350px;
	display: flex;
}


.navigation ul li {
	list-style: none;
	position: relative;
	width: 70px; /* ul: width 350 / 5 = 70 */
	height: 60px;
	z-index: 2;
}

.navigation ul li a {
	text-decoration: none;
	color:#555;
	
	position: relative;
	display: flex;
	justify-content: center;
	align-items: center;
	width: 100%;
	height: 100%;
}

.navigation ul li a .icon {
	position:relative;
	background: #fff;
	display:block;
	width: 55px;
	height: 55px;
	text-align: center;
	line-height: 65px;
	border-radius: 65px;
	color: #222327;
	font-size: 1.5em;
	transition: 0.5s;
	transition-delay: 0s;
}

.navigation ul li.active a .icon {
	background: var(--clr);
	color: #fff;
	transform: translatey(-27px);
	transition-delay: 0.25s;
}

.navigation ul li a .icon:before {
	content: '';
	position: absolute;
	top: 10px;
	left: 0;
	width: 100%;
	height: 100%;
	background: var(--clr);
	border-radius: 50%;
	filter: blur(5px);
	opacity:0;
	transition: .5s;
	transition-delay: 0.15s;
}

.navigation ul li.active a .icon:before {
	opacity: 0.5;
	transition-delay: 0.25s;
}

.indicator {
	position: absolute;
	top: -35px;
	width: 70px;
	height: 70px;
	background: #fff;
	border-radius: 50%;
	z-index: 1;
	transition: 0.5s;
}

.indicator::before {
	content: '';
	position: absolute;
	top: 5px;
	left: -27.5px;
	width: 30px;
	height: 30px;
	border-radius: 50%;
	box-shadow: 15px 18px #fff
}

.indicator::after {
	content: '';
	position: absolute;
	top: 5px;
	right: -27.5px;
	width: 30px;
	height: 30px;
	border-radius: 50%;
	box-shadow: -15px 18px #fff
}

.navigation ul li:nth-child(1).active ~ .indicator {
	transform: translatex(calc(70px * 0));
}

.navigation ul li:nth-child(2).active ~ .indicator {
	transform: translatex(calc(70px * 1));
}

.navigation ul li:nth-child(3).active ~ .indicator {
	transform: translatex(calc(70px * 2));
}

.navigation ul li:nth-child(4).active ~ .indicator {
	transform: translatex(calc(70px * 3));
}

.navigation ul li:nth-child(5).active ~ .indicator {
	transform: translatex(calc(70px * 4));
}