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!
Insecure Resource

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CSS

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JavaScript

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HTML 

              
                <div class="container">
   <div class="column">
     <p>what? no. we can't stop here. this is bat country. we're not sheep! giddy-up... <a href="#" class="thick-underline">thick underline</a> things like seeing their dead grandmother crawling up their leg with a knife in her teeth.</p> <p>but no one should be asked to handle this trip. well, then, i confess, it is my intention <a href="#" class="underline-slide">border slides in from left</a> in tortuga, raid, pillage, plunder and otherwise pilfer my weasely black guts out. me? i'm dishonest, and a dishonest man you can always trust to be dishonest.</p>
  </div>
  
  <div class="column">
    <p><a href="#" class="background-slide">Background slides in from left</a> we are very much alike, you and i, i and you... us. <a href="#" class="growing-border">Border slides in/out smoothly</a>, you and i, i and you... us. giddy-up... no, no this way... good horsey. we had two bags of grass, seventy-five pellets of mescaline, five sheets of this and another <a href="#" class="highlighted">highlighted effect</a>, a saltshaker half-full of cocaine, and a whole galaxy of multi-colored uppers, downers, screamers, laughers... do you like my meadow? try some of my grass! please have a blade, please do, <a href="#" class="border-grow-center">centered border grow</a> and so darn good looking!</p></div>
</div>
!

CSS 

              
                @import "compass/css3";

body {
  line-height: 1.75em;
  font-size: 1.1em;
  color: #333;
  background: #f3f3f3;
}

.container {
  max-width: 67em;
  margin: 0 auto;
  display: flex;
  flex-wrap: no-wrap;
  @media (max-width: 768px) {
    flex-wrap: wrap;
  }
}

.column {
  padding: 0 30px;
  width: 45%;
    @media (max-width: 768px) {
      width: 100%;
    }
}

a {
  text-decoration: none;
}

.thick-underline {
  border-bottom: 1px solid #c9e27f;
  box-shadow: inset 0 -7px 0 #c9e27f;
  color: rgba(15, 35, 59, .55);
  transition: all .25s ease-in-out;
  padding: 2px 2px 0 2px;
  &:hover {
    background-color: #c9e27f;
  }
}

.highlighted {
  box-shadow: inset 0 -.45em .85em #f1e12d;
  color: black; 
  transition: box-shadow .25s cubic-bezier(.32,.75,.25,1);
  &:hover {
    box-shadow: inset 0 -1.15em 0 #f1e12d;
  }
}

.underline-slide, .background-slide {
  color: #3588b4;
  position: relative;
  padding-bottom: 2px;
  &:after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    height: 2px;
    background-color: #6ebde7;
    width: 0%;
    display: block;
    transition: width .5s ease-in-out;
  }
  &:hover {
    color: black;
    &:after {
      width: 100%;
    }
  }
}

.background-slide {
  color: #e76ea7;
  z-index: 3;
  &:after {
    background: rgba(231, 110, 167, .4);
    height: 1.25em;
    z-index: -1;
  }
  &:hover {
    color: black;
  }
}

.growing-border {
  color: #e44040;
  padding-bottom: 2px;
  border-bottom: 0px solid black;
  transition: all .2s ease-in-out;
  &:hover {
    border-bottom-width: 3px;
  }
}

.border-grow-center {
  color: #994cb9;
  position: relative;
  padding-bottom: 2px;
  //transition: all .5s ease-in-out;
  &:after {
    content: '';
    height: 2px;
    background: #742794;
    width: 0;
    position: absolute;
    bottom: 0;
    left: 0;
  }
  &:hover {
    &:after {
      width: 100%;
      animation-duration: .8s;
      animation-name: bordergrow;
      animation-iteration-count: 1;
    }
  }
}

@keyframes bordergrow {
  0% {
    left: 50%;
    width: 10%;
  }

  100% {
    left: 0;
    width: 100%;
  }
}
!

JS 

              
                //IMPORTANT NOTE!
// The "border slides in from left", "background slides in from left" and "centered border grow" will NOT work if the link is more than one line. These work best on single word links or links that will not have a line break.
!
999px

Console