$nav-width: 200px;

$box-shadow-1: 0 3px 6px rgba(0,0,0,0.16), 0 3px 6px rgba(0,0,0,0.23);
$box-shadow-2: 0 10px 20px rgba(0,0,0,0.19), 0 6px 6px rgba(0,0,0,0.23);

body{
  background: lightgrey;
}

#main-nav{
  position: fixed;
  top: 0;
  left: 0;
  width: $nav-width;
  height: 100%;
  padding: 20px 0;
  background: #212121;
  color: white;
  box-shadow: $box-shadow-1;
  box-sizing: border-box;

  h3{
    text-align: center;
  }

  ul{
    list-style: none;

    li{
      margin: 0;
      border-bottom: 1px solid #999;

      &:first-child{
        border-top: 1px solid #999;
      }
    }

    a{
      display: block;
      box-sizing: border-box;
      width: $nav-width;
      padding: 10px 15px;
      color: limegreen;
      font-size: 2.5rem;
      text-decoration: none;
      transition: all 230ms ease-in-out;

      &:hover{
        background: rgba(255, 255, 255, 0.1);
      }
    }
  }
}

#main-wrapper{
  max-width: 1200px;
  margin-top: 25px;
  padding: 20px 30px;
  background: white;
  border-radius: 5px;
  box-shadow: $box-shadow-2;
}