@import url(http://fonts.lug.ustc.edu.cn/css?family=Noto+Sans);
  
*, *:before, *:after {  box-sizing: border-box; }

html, body {
  height: 100%;
  width: 100%;
}

$button-color: #65d3e3;
$top-grad: #2c3e50  ;
$bottom-grad: #51606f;

body{
  background: #fff;
  font-family: 'Noto Sans', sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

// Cover content with overlay when navigation is triggered. It would be nice to close the navigation if the overlay is clicked, but I am not sure how to code that.
#cover{
  opacity: 0;
  visibility: hidden;
  width: 100%;
  height: 100%;
  position: fixed;
  z-index: 1;
  transition: opacity 0.2s ease-in-out;

  &.display{
    background: rgba(0,0,0,0.2);
    opacity: 1;
    visibility: visible;
  }
}

#main-nav{
  background: linear-gradient(to bottom, $top-grad 0%, $bottom-grad 100%);
  z-index:1;
  height: 100%;
  width: 5em;
  position: fixed;
  overflow: hidden;
  transition: background 0.3s ease-in-out,
    width 0.3s ease;
  &.show{
    background: $button-color;
    width: 18em;
  }
}

#nav-button{
  background: $button-color;
  height: 3em;
  width: 3em; 
  border-radius: 50%;
  box-shadow: 0 2px 5px 0 rgba(0,0,0,.25);
  top: 1em;
  left: 1em;
  position: relative;
  user-select: none;
  color: #333;
  transition: all 0.3s ease-in-out;
  overflow: hidden;
  
  .fa{
    position: absolute;
    top: 0;
    left: 0.2em;
    right: 0;
    bottom: 0;
    margin: auto;
    display: block;
    width: 1em;
    height: 1em;
    font-size: 1em;
    opacity: 1;
    transition: opacity 0.4s ease-in-out;
  }
  
  &:hover{
    cursor:pointer;
    box-shadow: 0 7px 15px 0 rgba(0,0,0,.3);
    color: #222;
  }
  
  &.width{ 
    width: 80em;
    height: 80em;
    top: -37.5em;
    left: -37.5em;
    box-shadow: none;
    //animation: curve 1s linear;
    //animation-fill-mode: forwards;
    
    &:before {
      content:'';
      display: block;
      width: 0.4em;
      height: 0.4em;
      border-radius: 50%;
      position: absolute;
      top: 0;
      left: 0;
      right: 0;
      bottom: 0;
      margin: auto;
      animation: color 0.3s linear;
    }
  }
}

@keyframes color {
  0% {
      box-shadow: 0;
	}
	30% {
      box-shadow: 0 0 10px 25px rgba(12,121,137,0.5); /* feather / spread */
	}
}

/*@keyframes curve {
  0% {
		transform: rotate(0deg)
		           translate(0px)
		           rotate(0deg);
	}
	100% {
		transform: rotate(60deg)
		           translate(200px) 
		           rotate(-60deg);
	}
}*/

#nav-list{
  position: absolute;
  top: 7em; 
  padding: 0 0 0 2em;
  opacity: 0;
  width: 100%;
  transition: opacity 0.2s ease;
  //transition-delay: 0s;

  a{
    color: #444;
    text-decoration: none;
    font-size: 0.9em;
    display: block;
    width :100%;
    padding: 1.2em 0;
    transition: color 0.2s ease-in-out;
    &:hover{
      color: #000;
    }
  }
  
  &.nav-show{
    opacity: 1;
  }
}

// Extras
#content{
  padding: 0 0 0 7em;
  h1{
    padding: 1.25em 0;
    letter-spacing: 0.03em;
    font-size: 1.4em;
  }
}