index.css

* {
	
	padding: 0;
	margin: 0;
}
.container {
	
	display: flex;
	justify-content: center;
	align-items: center;
	
	flex-direction: column;
	
	height: 100vh;
	background-image: url("https://pic1.zhimg.com/80/v2-f62fa4868599f3f2e74c329696e7daec_1440w.jpg?source=1940ef5c");
}
.container a {

	position: relative;
	
	display: block;
	width: 140px;
	height: 60px;
	float:left;
	line-height: 60px;
	text-align: center;
	margin: 40px;
	color: aqua;
	font-size: 20px;

	text-decoration: none;
	
	transition: all 0.3s ease-in-out;

	filter: hue-rotate(calc(var(--i) * 60deg));
}
.container a::before,
.container a::after {
	
	content: "";
	position: absolute;
	width: 20px;
	height: 20px;
	border: 2px solid aqua;
	
	transition: all 0.3s ease-in-out 0.3s;
}
.container a::before {
	top: 0;
	left: 0;
	
	border-right: 0;
	border-bottom: 0;
}
.container a::after {
	right: 0;
	bottom: 0;
	
	border-top: 0;
	border-left: 0;
}
.container a:hover {
	background-color: aqua;
	color: #000;
	
	box-shadow: 0 0 50px aqua;
	
	-webkit-box-reflect: below 1px
		linear-gradient(transparent, rgba(0, 0, 0, 0.3));
	
	transition-delay: 0.4s;
}

.container a:hover::before,
.container a:hover::after {
	width: 138px;
	height: 58px;
	transition-delay: 0s;
}