html, body {
    margin: 0;
    padding: 0;
    background-color: black;
    font-family: 'Archivo Narrow', sans-serif;
}

#main-nav {
    background-color: black;
    height: 10%;
}

#main-nav ul {
    list-style: none;
    margin: 2% 0px;
    padding: 0px 10%;
    display: flex;
    justify-content: space-between;
}

#logo {
    width: 5%;
}

#logo img {
    width: 100%;
}

#main-nav ul li a {
    display: inline-block;
    text-decoration: none;
    color: white;
    font-size: 1.2rem;
    letter-spacing: .2rem;
    position: relative;
}

#main-nav ul li a,
#main-nav ul li a:before, 
#main-nav ul li a:after {
    transition: all .5s;
}

nav ul li a:hover {
    color: white;
  }

#main-nav ul li a:after {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  margin: auto;
  width: 0%;
  content: '.';
  color: transparent;
  background: white;
  height: 1px;
}

#main-nav ul li a:hover:after {
    width: 100%;
}

#nav-home, #nav-net, #nav-com, #nav-hard, #nav-source {
    padding-top: 1.5%;
}

#header-img-container img {
    width: 100%;
    object-fit: contain;
}

#header-img-container {
    width: 100%;
    height: 700px;
    overflow: hidden;
}

#net-banner {
    width: 100%;
    height: 700px;
    background-image: url(https://www.nasa.gov/sites/default/files/thumbnails/image/iss068e054895_orig.jpg);
    background-size: cover;
    background-position: 50%;
}

#net-title {
    width: 30%;
    margin: 0;
    color: white;
    font-size: 4rem;
    font-weight: 600;
    letter-spacing: .3rem;
    padding: 10% 0px 0px 5%;
}

#net-learn {
    width: 10%;
    text-align: center;
    margin: 10% 0px 0px 82%;
    color: white;
    font-size: 1.5rem;
    font-weight: bold;
    letter-spacing: .2rem;
    border: 3px solid white;
    padding: .2rem;
    border-radius: 30px;
}

#com-banner {
    width: 100%;
    height: 700px;
    background-image: url(https://www.thestatesman.com/wp-content/uploads/2017/08/1491978973-iss.jpg);
    background-size: cover;
    background-position: 50%;
}

#com-title {
    width: 80%;
    margin: 0;
    color: white;
    font-size: 4rem;
    font-weight: 600;
    text-align: center;
    letter-spacing: .3rem;
    padding: 3% 0px 0px 10%;
}

#com-learn {
    width: 10%;
    text-align: center;
    margin: 2% 0px 0px 45%;
    color: white;
    font-size: 1.5rem;
    font-weight: bold;
    letter-spacing: .2rem;
    border: 3px solid white;
    padding: .2rem;
    border-radius: 30px;
}

#hard-banner {
    width: 100%;
    height: 700px;
    background-image: url(https://www.ralspace.stfc.ac.uk/Gallery/12mantenna_at_dusk.jpg);
    background-size: cover;
    background-position: 50%;
    margin-bottom: 6%;
}

#hard-title {
    width: 10%;
    margin: 0;
    color: white;
    font-size: 4rem;
    font-weight: 600;
    text-align: center;
    letter-spacing: .3rem;
    padding: 5% 0px 0px 70%;
}

#hard-learn {
    width: 10%;
    text-align: center;
    margin: 25% 0px 0px 7%;
    color: white;
    font-size: 1.5rem;
    font-weight: bold;
    letter-spacing: .2rem;
    border: 3px solid white;
    padding: .2rem;
    border-radius: 30px;
}