body {
  margin: 0;
  height: 400vw; /* enough to scroll */
  font-family: serif;
  background: #000033;
}

.bgcolor {
  position: fixed;
  top: 0;
  left: 40vw;
  width: 300vw;
  height: 100%;
  z-index: -2;
  background: #000033;
}

.pseudo-bg {
  position: fixed;
  top: 0;
  width: auto;
  height: 100vh;
  z-index: -1;
  display: flex;
}
.pseudo-bg img {
  height: auto;
}

.content {
  position: relative;
  z-index: 1;
}

section {
  display: flex;
  justify-content: center;
  align-items: center;
}

.scroll-element {
  position: absolute;
  bottom: 150px;
  opacity: 0;
  transition: opacity 0.5s ease;
}
  .scroll-element img {
    display: block;
    cursor: help;
    max-width: 300px;
    height: auto;
    image-rendering: pixelated;
  }
  .scroll-element a {
    position: relative;
    display: inline-block;
    text-decoration: none;
  }
  .scroll-element .title {
    position: absolute;
    bottom: -30px;
    left: 50%;
    transform: translateX(-50%);
    font-family: serif;
    font-size: 1rem;
    background-color: blue;
    color: white;
    opacity: 0;
    transition: opacity 0.5s ease, transform 0.5s ease;
    pointer-events: none; /* hover triggers via img */
  }
  .scroll-element a:hover .title {
    font-family: serif;
    font-style: italic;
    opacity: 1;
    transform: translateX(-50%) translateY(-5px);
  }

.sidenav {
  width: 150px;
  border-style: solid;
  border-width: thin;
  border-color: red;
  background-color: white;
  position: fixed;
  vertical-align: middle;
  top: 50%;
  left: 20px;
  overflow-x: hidden;
  transform: translateY(-50%);
  z-index: 10;
  font-family: serif;
}
  .subtitle {
    font-family: "Times New Roman", serif;
    font-style: italic;
    font-size: 28px;
    font-weight: normal;
    padding-top:0%;
    margin: 5%;
    color: blue;
  }
  .sidenav ul {
    list-style: none;
    margin: 5%;
    padding: 0;
    font-family: serif;
    color: blue;
  }
  .sidenav li {
    margin: auto;
    font-family: serif;
  }
  .sidenav a {
    font-family: serif;
    text-decoration: none;
    font-style: normal;
    color: blue;
    font-size: 20px;
    transition: color 0.2s ease;
  }
  .sidenav a:hover {
    font-style: italic;
    color: red;
    font-family: serif;
  }
  .sidenav a:visited {
    font-style: normal;
    color: blue;
    text-decoration: none;
  }