<div class="panels">
<div class="panels__container">
  <a href="#" class="panel">
    <div class="panel__content" style="background-image: url(https://unsplash.it/1000/1100/?image=786);">
    <h3 class="panel__title">EXPLORE</h3>
    </div>
  </a>
  <a href="#" class="panel">
    <div class="panel__content" style="background-image: url(https://unsplash.it/1000/1100/?image=883)">
    <h3 class="panel__title">DISCOVER</h3>
    </div>
  </a>
</div>
</div>

@duration: 1s;
@ease: cubic-bezier(.6,.0,.2,1);

@offsetSize: 10%;
@contentOffset: @offsetSize * 1.4;
/* @offsetSize * 2 means the content won't appear to move at all. Set to a lower value for squishing effects. */

@textColor: #FFF;
@overlayColor: #000;
@highlightColor: #FFC12D;
@borderColor: @highlightColor;

/*////////////////////////////////////////*/
/* Layout */

.panels {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background: @overlayColor;
  pointer-events: none;
}

.panels__container {
  display: flex;
  justify-content: center;
  align-items: stretch; 
  
  height: 100%;
  width: unit( 100 + (@offsetSize * 2),%);
  margin: 0 -(@offsetSize);
  visibility: hidden; 
}

.panel {
  display: inline-block;
  height: 100%;
  visibility: visible;
  position: relative; 
  overflow: hidden;
  flex: 1;
  cursor: pointer;
  text-decoration: none;
}

/*////////////////////////////////////////*/
/* Image/Text Container */

.panel__content {
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: center center no-repeat;
  background-size: cover;
  
  &:before {
    content: '';
    position: absolute;
    top: 0; right: 0; bottom: 0; left: 0;
    background: @overlayColor;
    opacity: 0.5;
    transition: opacity @duration @ease;
  }
}

/*////////////////////////////////////////*/
/* Title */

.panel__title {
  pointer-events: auto;
  color: @textColor;
  position: relative;
  z-index: 1;
  transition: color @duration @ease;
  
  &:before {
    content: '';
    position: absolute;
    top: 0; right: 0; bottom: 0; left: 0;
    background: @overlayColor;
    background: fade(@overlayColor,70%);
    border: solid 2px @borderColor;
    z-index: -1;
    padding: 0.5em 1em;
    margin: -0.5em -1em;
    
    opacity: 0;
    transform: scale(0.9);
    transition: all @duration @ease;
    transition-property: opacity, transform;
  }
}

/*////////////////////////////////////////*/
/* Hover States */

.panel {
  transform: translate3d(0,0,0);
  transition: transform @duration @ease;
  
  .panel__content { 
    transform: translateX(@offsetSize);
    transition: transform @duration @ease;
  }
  
  &:last-child .panel__content {
    transform: translateX(-@offsetSize);
  }
  
  /* Inactive panel */
  .panels:hover & {
    transform: translate3d(-@offsetSize, 0, 0); 
      
    .panel__content { 
      transform: translateX(@contentOffset);             
      &:before { opacity: 0.7; }
    }
  }
  
  /* Override styles for an inactive panel AFTER the hovered panel */
  .panels &:hover ~ & { 
    transform: translate3d(@offsetSize, 0, 0);
    
    .panel__content { 
      transform: translateX(-@contentOffset);
    }
  }
  
  /* Active panel */
  .panels &:hover { 
    z-index: 2;
    transform: translate3d(@offsetSize,0,0);
    pointer-events: auto;
    
    &:last-child { transform: translate3d(-@offsetSize,0,0); }
    
    .panel__content { 
      transform: translateX(0%);
      &:before { opacity: 0; }
    }
    
    .panel__title {
      color: @highlightColor;

      &:before {
        opacity: 1;
        transform: scale(1);
      }
    }
  } 
}

/*////////////////////////////////////////*/
/* Vertical layout */

.panels--stacked {
  
  .panels__container {
    width: 100%;
    height: unit( 100 + (@offsetSize * 2),%);
    margin: -(@offsetSize) 0;
    flex-direction: column;
  }

  .panel {
    height: 50%;
    width: 100%;
    transform: translate3d(0, 0, 0);

    .panel__content {
      transform: translate3d(0, @offsetSize, 0);
    }

    &:last-child .panel__content {
      transform: translate3d(0, -@offsetSize,0);
    }
  }
  
    /* Inactive panel */
  &:hover .panel {
    transform: translate3d(0, -@offsetSize, 0);

    .panel__content {
      transform: translate3d(0, @contentOffset, 0);
    }
  }

  /* Override styles for an inactive panel AFTER the hovered panel */
  & .panel:hover ~ .panel {
    transform: translate3d(0, @offsetSize, 0);

    .panel__content {
      transform: translate3d(0, -@contentOffset, 0);
    }
  }

  /* Active panel */
  & .panel:hover {
    transform: translate3d(0, @offsetSize, 0);

    &:last-child { transform: translate3d(0, -@offsetSize, 0); }

    .panel__content {
      transform: translate3d(0, 0, 0);
    }
  }
}

/* Responsive */

@media (max-width: 550px) {
  .panels { .panels--stacked; }
}

/*////////////////////////////////////////*/
/* Specific Design Setup */

@import 'https://fonts.googleapis.com/css?family=Oswald';

.panel__title {
  font-family: 'Oswald', sans-serif;
  text-transform: uppercase;
  font-size: 2.5em;
  letter-spacing: 0.1em;
  
  @media (max-width: 800px) {
    font-size: 1.5em;
  }
  @media (max-width: 600px) {
    font-size: 1.25em;
  }
}

html, body { height: 100%; }

/* Nothing here! */