body {
    margin: 0px;
    padding: 0px;
}

nav ul {
    position: fixed;
    top: 0;
    width: 300px;
    height: 100%;
    overflow: auto;
    background-color: #f1f1f1;
    list-style-type: none;
    margin: 0;
    padding: 0;
    padding-top: 100px;
  }

nav ul li {
    width: 200px;
    margin-left:auto;
    margin-right: auto;
    margin-top: 10px;
    margin-bottom: 10px;
    padding: 8px;
}

  #content {
    margin-left: 200px;
  }

  .container {
      column-count: 3;
  }

  article {
      padding: 30px;
  }

  header {
      position: sticky;
      top: 0;
      background-color: #f0f0f0;
      height: 80px;
      z-index: 10;
  }

  header div {
      position: relative;
      top: 20%;
      width:400px;
      margin-left: auto;
      margin-right: auto;
      text-align: center;
      padding-top:10px;
      font-size: 1.75rem;
  }

.image-container {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 600px;  
    position: relative;  
}


  .transition-off-screen {
    opacity: 0;
    transform: translateX(-5000px);
    
  }

 img {
    width: 500px;
    position: absolute;
    top:25%;
    left: 30%;
  }

  .img-activate {
    -webkit-transition: opacity 1s ease-in-out;
    -moz-transition: opacity 1s ease-in-out;
    -o-transition: opacity 1s ease-in-out;
    transition: opacity 1s ease-in-out;  
  }


  .glow-on-hover {
    width: 200px;
    height: 50px;
    border: none;
    outline: none;
    color: #fff;
    background: #111;
    cursor: pointer;
    position: relative;
    z-index: 0;
    border-radius: 10px;
}

.glow-on-hover:before {
    content: '';
    background: linear-gradient(45deg, #fc58d8, #ff00c8, #fc58d8);
    position: absolute;
    top: -2px;
    left:-2px;
    background-size: 400%;
    z-index: -1;
    filter: blur(5px);
    width: calc(100% + 4px);
    height: calc(100% + 4px);
    animation: glowing 10s linear infinite;
    opacity: 0;
    transition: opacity .3s ease-in-out;
    border-radius: 10px;
}

.glow-on-hover:active {
    color: #000
}

.glow-on-hover:active:after {
    background: transparent;
} 

.glow-on-hover:hover:before {
    opacity: 1;
}

.glow-on-hover:after {
    z-index: -1;
    content: '';
    position: absolute;
    width: 100%;
    height: 100%;
    background: #111;
    left: 0;
    top: 0;
    border-radius: 10px;
}

@keyframes glowing {
    0% { background-position: 0 0; }
    50% { background-position: 400% 0; }
    100% { background-position: 0 0; }
}

@media only screen and (max-width: 800px) {
  img {
    width: 250px;
    position: absolute;
    top:25%;
    left: 30%;
  }
}