<header class="pen-intro">
  <h1>Single Element Link Styles</h1>
  <p>These have been made to specifically be a single element link - use of pseudo but no wrapping spans here. Have tried to keep relatively browser supported.</p>
  <p><small>(I have kept the styles independent of each other so that could be taken individually easily so there is some repetition)</small></p>
</header>

<hr />

<div class="button-container">
  <h2>Draw Outline</h2>
  <a href="#" class="draw-outline">Single Outline</a>
  <a href="#" class="draw-outline draw-outline--tandem">Tandem Outline</a>
</div>

<hr />

<div class="button-container">
  <h2>Swipe Fill</h2>
  <a href="#" class="swipe-fill swipe-fill--up">Swipe Fill Up</a>
  <a href="#" class="swipe-fill swipe-fill--down">Swipe Fill Down</a>
  <a href="#" class="swipe-fill swipe-fill--left">Swipe Fill Left</a>
  <a href="#" class="swipe-fill swipe-fill--right">Swipe Fill Right</a>
</div>

<hr />
<div class="button-container">
  <h2>Box Fill</h2>
  <a href="#" class="box-fill">Box Fill In</a>
  <a href="#" class="box-fill box-fill--out">Box Fill Out</a>
</div>

<hr />

<div class="button-container">
  <h2>Cross Fade</h2>
  <a href="#" class="cross-fade">Button One</a>
</div>

<hr />

<h2>Text Underline Animation</h2>

<p>Inspired by things that have seen from <a href="https://medium.design/crafting-link-underlines-on-medium-7c03a9274f9" target="_blank">Medium</a> and other peoples <a href="https://codepen.io/ghepting/pen/tLnHK" target="_blank">pens</a> but with an added attempt at bringing in some animation. Currently limited to a link that is in total 10000px wide across all lines but want to find a better way to do that.</p>

<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. <a href="javascript:void(0)">Recusandae alias laboriosam quisquam, minima vero unde facilis eius, perspiciatis impedit modi amet doloremque</a>, optio voluptatibus <a href="javascript:void(0)">veritatis fugiat corrupti ullam pariatur</a> quasi! Lorem ipsum dolor sit amet, consectetur adipisicing elit. Quos odit, aliquam porro tempore amet voluptas voluptatibus aut consectetur, animi sit unde eos molestiae est minus sed doloribus repellendus error similique?</p>

////////////////////////////////////////
// DRAW OUTLINE 
////////////////////////////////////////

$outline-border-width: 2px;
$outline-border-color: black;
$sec-outline-border-color: #37b2b2;
$outline-button-padding: 16px 28px;
$outline-text-color: black;
$sec-outline-text-color: #37b2b2;
$outline-transition-time: 1.5s;
$outline-fade: 0.35s;
$outline-active-scale: 1.05;

.draw-outline {
  display: inline-block;
  padding: $outline-button-padding;
  border: $outline-border-width $outline-border-color solid;
  text-align: center;
  text-decoration: none;
  color: $outline-text-color;
  position: relative;
  transition: border-color 0.35s ease-in-out;
  z-index: 1;
  
  &:before,
  &:after {
    content: '';
    position: absolute;
    width: 0px;
    height: 0px;
    box-sizing: content-box;
    z-index: -1;
    transition: transform 0.25s ease-in-out;
    padding-left: $outline-border-width;
  }
  
  &:before {
    top: -$outline-border-width;
    left: -$outline-border-width;
    border-top: $outline-border-width transparent solid;
    border-right: $outline-border-width transparent solid;
  }
  
  &:after {
    bottom: -$outline-border-width;
    right: -$outline-border-width;
    border-bottom: $outline-border-width transparent solid;
    border-left: $outline-border-width transparent solid;
  }
  
  &:hover {
    color: $sec-outline-text-color;
    transition: color $outline-fade ease-in-out,  border-color $outline-fade ease-in-out;
    border-color: $outline-border-color;
    animation: outline-reset $outline-fade 1  forwards;
    &:before {
      animation: top-right-border $outline-transition-time/2 1 $outline-fade forwards;
    }
    &:after {
      animation: bottom-left-border $outline-transition-time/2 1 ($outline-transition-time/2)+$outline-fade forwards;
    }
  } 
  &--tandem:hover {
    &:after {
      animation: bottom-left-border $outline-transition-time/2 1 $outline-fade forwards;
    }  
  }
  &:active {
    &:before,
    &:after {
      transform: scale($outline-active-scale);
    }
  }
}

@keyframes outline-reset {
  0% {
    border-color: $outline-border-color;
  }
  100% {
    border-color: transparent;
  }
}


@keyframes top-right-border {
  0% {
    border-color: $sec-outline-border-color;
    width: 0px;
    height: 0;
  }
  50% {
    width: 100%;
    height: 0;
  }
  100% {
    border-color: $sec-outline-border-color;
    width: 100%;
    height: 100%;
  }
}

@keyframes bottom-left-border {
  0% {
    border-color: $sec-outline-border-color;
    width: 0px;
    height: 0;
  }
  50% {
    width: 100%;
    height: 0;
  }
  100% {
    border-color: $sec-outline-border-color;
    width: 100%;
    height: 100%;
  }
}



////////////////////////////////////////
// SWIPE FILL
////////////////////////////////////////

$swipe-fill-border-width: 2px;
$swipe-fill-border-color: black;
$sec-swipe-fill-border-color: black;
$swipe-fill-button-padding: 16px 28px;
$swipe-fill-text-color: black;
$sec-swipe-fill-text-color: white;
$swipe-fill-border-radius: 0px;
$swipe-fill-background: white;
$sec-swipe-fill-background: #666;
$swipe-fill-transition-time: 0.25s;

.swipe-fill {
  display: inline-block;
  padding: $swipe-fill-button-padding;
  border: $swipe-fill-border-width $swipe-fill-border-color solid;
  text-align: center;
  text-decoration: none;
  color: $swipe-fill-text-color;
  background: $swipe-fill-background;
  position: relative;
  overflow: hidden;
  transition: color $swipe-fill-transition-time ease-in-out,  border-color $swipe-fill-transition-time ease-in-out;
  z-index: 1;
  border-radius: $swipe-fill-border-radius;
  
  &:before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: $sec-swipe-fill-background;
    transition: transform $swipe-fill-transition-time ease-in-out;
    z-index: -1;
  }
  
  &--up {
    &:before {
      transform: translate3d(0, 100%, 0);
    }
  }
  
  &--down {
    &:before {
      transform: translate3d(0, -100%, 0);
    }
  }
  
  &--left {
    &:before {
      transform: translate3d(-100%, 0, 0);
    }
  }
  
  &--right {
    &:before {
      transform: translate3d(100%, 0, 0);
    }
  }
  
  &:hover {
    color: $sec-swipe-fill-text-color;
    border: $swipe-fill-border-width $sec-swipe-fill-border-color solid;
    &:before {
      transform: translate3d(0, 0, 0);
    }
  }
}



////////////////////////////////////////
// BOX FILL 
////////////////////////////////////////

$box-fill-border-width: 2px;
$box-fill-border-color: black;
$sec-box-fill-border-color: black;
$box-fill-button-padding: 16px 28px;
$box-fill-text-color: black;
$sec-box-fill-text-color: white;
$box-fill-border-radius: 0px;
$box-fill-background: white;
$sec-box-fill-background: #666;
$box-fill-transition-time: 0.35s;

.box-fill {
  display: inline-block;
  padding: $box-fill-button-padding;
  border: $box-fill-border-width $box-fill-border-color solid;
  text-align: center;
  text-decoration: none;
  color: $box-fill-text-color;
  position: relative;
  overflow: hidden;
  background: $box-fill-background;
  transition: color $box-fill-transition-time ease-in-out;
  z-index: 1;
  border-radius: $box-fill-border-radius;
  
  &:before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: $sec-box-fill-background;
    transition: transform $box-fill-transition-time ease-in-out, opacity $box-fill-transition-time ease-in-out;
    transform: scale(0);
    z-index: -1;
    opacity: 0;
  }
  
  &:hover {
    color: $sec-box-fill-text-color;
    &:before {
      transform: scale(1);
      opacity: 1;
    }
  }

  &--out {
    color: $sec-box-fill-text-color;
    &:before {
      transform: scale(1);
      opacity: 1;
    }
    &:hover {
      color: $box-fill-text-color;
    }
    &:hover:before {
      transform: scale(0);
      opacity: 0;
    }
  }
}



////////////////////////////////////////
// CROSS FADE 
////////////////////////////////////////

$cross-fade-border-width: 2px;
$cross-fade-border-color: black;
$sec-cross-fade-border-color: black;
$cross-fade-button-padding: 16px 28px;
$cross-fade-text-color: black;
$sec-cross-fade-text-color: white;
$cross-fade-border-radius: 0px;
$cross-fade-background: white;
$sec-cross-fade-background: #666;
$cross-fade-transition-time: 0.75s;

.cross-fade {
  display: inline-block;
  padding: $cross-fade-button-padding;
  border: $cross-fade-border-width $cross-fade-border-color solid;
  text-align: center;
  text-decoration: none;
  color: $cross-fade-text-color;
  position: relative;
  overflow: hidden;
  transition: color $cross-fade-transition-time ease-in-out;
  z-index: 1;
  border-radius: $cross-fade-border-radius;
  
  &:before,
  &:after {
    content: '';
    position: absolute;
    top: 0;
    left: -25%;
    width: 150%;
    height: 100%;
    background: rgba($sec-cross-fade-background, 0.5);
    transition: transform $cross-fade-transition-time ease-in-out;
    z-index: -1;
  }
  
  &:before {
    transform: translate3d(100%, 0, 0) skew(20deg);
    transform-origin: 0 0;
  }
  
  &:after {
    transform: translate3d(-100%, 0, 0) skew(20deg);
    transform-origin: 100% 100%;
  }
  
  &:hover {
    color: $sec-cross-fade-text-color;
    &:before,
    &:after {
      transform: translate3d(0, 0, 0) skew(20deg);
    }
  }
}



////////////////////////////////////////
// UNDERLINE ANIMATION 
////////////////////////////////////////

$link-color: #37b2b2;

a:not([class]) {
  text-shadow: rgb(255, 255, 255) 1px 0px 0px, rgb(255, 255, 255) 0.540302px 0.841471px 0px, rgb(255, 255, 255) -0.416147px 0.909297px 0px, rgb(255, 255, 255) -0.989992px 0.14112px 0px, rgb(255, 255, 255) -0.653644px -0.756802px 0px, rgb(255, 255, 255) 0.283662px -0.958924px 0px, rgb(255, 255, 255) 0.96017px -0.279415px 0px;
  text-decoration: none;
  background-image: linear-gradient($link-color 50%, $link-color 50%);
  background-size: 10000px 1px;
  color: $link-color;
  background-repeat: no-repeat;
  background-position: 0 1em;
  background-position: -10000px 1em;
  &:hover {
    background-position: 0 1em;
    transition: background-position 2s ease-in-out;
  }
}










////////////////////////////////////////
// GLOBAL SETUP 
////////////////////////////////////////
$wrapper-max-width: 1000px;

body {
  font-family: sans-serif;
  max-width: $wrapper-max-width;
  margin: 0 auto;
  padding: 30px;
  font-family: 'Maven Pro', sans-serif;
  text-align: center;
}

h1 {
  font-size: 2.8rem;
}
h2 {
  font-size: 2rem;
}
h1,h2 {
  font-family: 'Yrsa', cursive;
}

p {
  font-size: 1.25rem;
  line-height: 1.75rem;
}

hr {
  margin: 40px auto;
  max-width: 100px;
  display: block;
  height: 1px;
  border: 0;
  border-top: 1px solid #ccc;
  padding: 0; 
}

.pen-intro {
  text-align: center;
}

.button-container {
  a {
    margin: 0 10px;
  }
}