Pug Preporcessor SCSS border animation without svg

PURE CSS Using PUG Preprocessor + SCSS to create border animation without SVG

PUG HTML AND SCSS

HTML Code

Normal HTML (Compiled | Before converted to PUG)
<script src="https://cdnjs.cloudflare.com/ajax/libs/prefixfree/1.0.7/prefixfree.min.js"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/normalize/6.0.0/normalize.css"/>
<div class="bb"></div>
PUG CODE (After Converted from NORMAL HTML)
script(src='https://cdnjs.cloudflare.com/ajax/libs/prefixfree/1.0.7/prefixfree.min.js')
link(rel='stylesheet', href ='https://cdnjs.cloudflare.com/ajax/libs/normalize/6.0.0/normalize.css')

.bb

CSS Code:

NORMAL CSS (Before converted to SCSS):
.bb, .bb::before, .bb::after {
position: absolute;
top: 0;
bottom: 0;
left: 0;
right: 0;
}

.bb {
width: 200px;
height: 200px;
margin: auto;
background: url("https://blog.codepen.io/wp-content/uploads/2012/06/Button-White-Large.png") no-repeat 50%/70% rgba(0, 0, 0, 0.1);
color: #69ca62;
box-shadow: inset 0 0 0 1px rgba(105, 202, 98, 0.5);
}
.bb::before, .bb::after {
content: '';
z-index: -1;
margin: -5%;
box-shadow: inset 0 0 0 2px;
animation: clipMe 8s linear infinite;
}
.bb::before {
animation-delay: -4s;
}
.bb:hover::after, .bb:hover::before {
background-color: rgba(255, 0, 0, 0.3);
}

@keyframes clipMe {
0%, 100% {
clip: rect(0px, 220px, 2px, 0px);
}
25% {
clip: rect(0px, 2px, 220px, 0px);
}
50% {
clip: rect(218px, 220px, 220px, 0px);
}
75% {
clip: rect(0px, 220px, 220px, 218px);
}
}
html,
body {
height: 100%;
}

body {
position: relative;
background-color: #0f222b;
}

*,
*::before,
*::after {
box-sizing: border-box;
}
SCSS Code (After Converted from Normal CSS)
$anime-time: 8s;

$box-size: 200px;
$clip-distance: .05;
$clip-size: $box-size * (1 + $clip-distance * 2);
$path-width: 2px;

$main-color: #69ca62;

$codepen-logo-path: url('https://blog.codepen.io/wp-content/uploads/2012/06/Button-White-Large.png');

%full-fill {
position: absolute;
top: 0;
bottom: 0;
left: 0;
right: 0;
}

.bb {
@extend %full-fill;
width: $box-size;
height: $box-size;
margin: auto;
background: $codepen-logo-path no-repeat 50% / 70% rgba(#000, .1);
color: $main-color;
box-shadow: inset 0 0 0 1px rgba($main-color, .5);

&::before,
&::after {
@extend %full-fill;
content: '';
z-index: -1;
margin: -1 * $clip-distance * 100%;
box-shadow: inset 0 0 0 $path-width;
animation: clipMe $anime-time linear infinite;
}

&::before {
animation-delay: $anime-time * -.5;
}

// for debug
&:hover {
&::after,
&::before {
background-color: rgba(#f00, .3);
}
}

}

@keyframes clipMe {
0%, 100% {clip: rect(0px, $clip-size, $path-width, 0px); }
25% {clip: rect(0px, $path-width, $clip-size, 0px); }
50% {clip: rect($clip-size - $path-width, $clip-size, $clip-size, 0px); }
75% {clip: rect(0px, $clip-size, $clip-size, $clip-size - $path-width); }
}

/////

html,
body {
height: 100%;
}

body {
position: relative;
background-color: #0f222b;
}

*,
*::before,
*::after {
box-sizing: border-box;
}


Result DEMO: