%div.wrapper
  %div.bttn.out.cyan
    %span Infiniti
    %div.corners.top
    %div.corners.bottom

  %div.bttn.in
    %span Infinity
    %div.corners.top
    %div.corners.bottom

  %div.box.out
    %div.content
      %p Bacon ipsum dolor amet meatloaf corned beef frankfurter tongue
    %div.corners.top
    %div.corners.bottom
    
  %div.box.in
    %div.content
      %p Short ribs boudin cow landjaeger spare ribs cupim.
    %div.corners.top
    %div.corners.bottom
View Compiled
@import url(https://fonts.googleapis.com/css?family=Electrolize);

// settings
$text-color: #FFB902;
$line-color: #FFB902;
$line-size: 7;

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

// general
body {
  font-family: 'Electrolize', sans-serif;
  background: #070707;
  overflow: hidden;
}

// magic wrapper
.wrapper {
  // @include translateCenter;
  // text-align: center;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100%;
  width: 100%;
  
  > div {
    margin: 20px;
  }
}

//
//  Corners mixin (MAGIC BE HERE!)
//
@mixin line-corners($line-color: cyan, $line-size: 7, $line-type: out, $line-distance: 20) {
  position: absolute;
  width: 100%;
  
  transition-duration: 0.3s;
  
  // arrows
  &:before,
  &:after {
    content: '';
    
    position: absolute;
    
    width: $line-size + px;
    height: $line-size + px;
    
    border-color: $line-color;
    border-style: solid;
    
    // will-change: transform, opacity;
    transition-duration: 0.3s;
    transform: translateZ(0);
  }
  
  // top corners
  &.top {
    &:before { border-width: 1px 0 0 1px; }
    &:after { border-width: 1px 1px 0 0; }
  }
  
  // bottom corners
  &.bottom {
    &:before { border-width: 0 0 1px 1px; }
    &:after { border-width: 0 1px 1px 0; }
  }
  
  @if $line-type == out {
    &:before { left: 0; }
    &:after { right: 0; }
    &.top { top: 0; }
    &.bottom { bottom: $line-size + px; }    
  }
  
  @if $line-type == in {
    &:before { left: $line-distance + px; }
    &:after { right: $line-distance + px; }
    &.top { top: $line-distance + px; }
    &.bottom { bottom: ($line-distance + $line-size) + px; }
  }
}

@mixin line-corners-hover($line-size: 7, $line-type: out, $line-distance: 20) {
  @if $line-type == out {
    &:before { left: 0; }
    &:after { right: 0; }
    &.top { top: 0; }
    &.bottom { bottom: $line-size + px; }
  }
  
  @if $line-type == in {
    &:before { left: $line-distance + px; }
    &:after { right: $line-distance + px; }
    &.top { top: $line-distance + px; }
    &.bottom { bottom: ($line-distance + $line-size) + px; }
  }
}

// style: borders out (edge)
@mixin line-corners-out($line-color: cyan, $line-size: 7) {
  .corners { @include line-corners($line-color, $line-size, out); }
  &:hover {
    .corners { @include line-corners-hover($line-size, in); }
  }
}
  
// style: borders in
@mixin line-corners-in($line-color: cyan, $line-size: 7) {
  .corners { @include line-corners($line-color, $line-size, in); }
  &:hover {
    .corners { @include line-corners-hover($line-size, out); }
  }
}
//
// @end: Corners mixin
//

//
// magic buttons
//
.bttn {
  display: inline-block;
  vertical-align: middle;
  position: relative;

  // text
  span {
    display: block;
    padding: 30px;
    
    font-size: 30px;
    color: $text-color;
    text-transform: uppercase;

    // transition: all 0.3s ease-out;
  }
  
  &:hover {
    cursor: pointer;
  }
  
  // include corners
  &.out {
    @include line-corners-out(cyan);
  }
  
  &.in {
    @include line-corners-in($line-color);
  }
}

.bttn {
  //opacity: 0;

  //will-change: transform, opacity;
  //animation: fadeIn 0.6s 0.5s forwards ease-out;
  
  // cyan theme
  &.cyan {
    $theme-color: cyan;
    span { color: $theme-color; }
    .corners {
      &:after,
      &:before { border-color: $theme-color; }
    }
  }
}

//
//  magic box
//
.box {
  display: inline-block;
  vertical-align: middle;
  position: relative;
  
  width: 200px;
  
  .content {
    margin: 20px;
    padding: 20px;
    
    border: 1px dashed transparent;
    color: white;

    font-size: 14px;
    line-height: 1.3;
  }
  
  // include corners
  &.out {
    @include line-corners-out(cyan);
    .content {
      border-color: rgba(0, 255, 255, 0.5);
      color: cyan;
    }
  }
  
  &.in {
    @include line-corners-in($line-color);
    .content {
      border-color: rgba(255, 185, 2, 0.5);
      color: $text-color;
    }
  }
}

//
//  Animations
//
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(50%);
  }
  
  to {
    opacity: 1;
    transform: translateY(0%);
  }
}
View Compiled
Run Pen

External CSS

  1. https://codepen.io/NyX/pen/AykgJ

External JavaScript

This Pen doesn't use any external JavaScript resources.