body
{
margin: 0;
padding: 0;
background:#0c002b;
font-family: sans-serif;
}
a{
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%,-50%);
color:#1670f0;
padding:30px;
letter-spacing:2px;
text-transform:uppercase;
text-decoration:none;
box-shadow:0 20px 50px rgba(0,0,0,.5);
overflow:hidden;
}
a:before
{
content: '';
position: absolute;
top: 2px;
left: 2px;
bottom: 2px;
width: 50%;
background: rgba(255,255,255,0.05);
}
a span:nth-child(1)
{
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 2px;
background: linear-gradient(to right,#0c002b,#1779ff);
animation: animate1 2s linear infinite;
}
@keyframes animate1
{
 0%
 {
   transform:translateX(-100%);
 
 }
 100%
 {
   transform:translateX(100%);
 
 }
}
a span:nth-child(2)
{
position: absolute;
top: 0;
right: 0;
width: 2px;
height: 100%;
background: linear-gradient(to bottom,#0c002b,#1779ff);
animation: animate2 2s linear infinite;
animation-delay: 1s;
}
@keyframes animate2 
{
 0%
 {
   transform:translateY(-100%);
 
 }
 100%
 {
   transform:translateY(100%);
 
 }
}
a span:nth-child(3)
{
position: absolute;
bottom: 0;
left: 0;
width: 100%;
height: 2px;
background: linear-gradient(to left,#0c002b,#1779ff);
animation: animate3 2s linear infinite;
}
@keyframes animate3
{
 0%
 {
   transform:translateX(100%);
 
 }
 100%
 {
   transform:translateX(-100%);
 
 }
}
a span:nth-child(4)
{
position: absolute;
top: 0;
left: 0;
width: 2px;
height: 100%;
background: linear-gradient(to top,#0c002b,#1779ff);
animation: animate4 2s linear infinite;
animation-delay: 1s;
}
@keyframes animate4 
{
 0%
 {
   transform:translateY(100%);
 
 }
 100%
 {
   transform:translateY(-100%);
 
 }
}