header {
  position: fixed;
  left: 0;
  top: 0;
  right: 0;
  min-height: 100px;
  display: flex;
  flex-flow: row nowrap;
  align-items: center;
  justify-content: center;
  background-color: rgba(0,0,0,0.75);
  backdrop-filter: blur(4px);
  z-index: 10;
}

header img.logo {
  width: 80px;
  margin: 10px;
  border-radius: 80px;
  background-color: rgba(255,255,255,0.8);
}

header nav {
  margin-left: 10px;
  flex-grow: 1;
}

header nav ul {
  list-style-type: none;
  display: flex;
  flex-flow: row nowrap;
  align-items: center;
}

header nav ul li:not(:last-child) {
  margin-right: 25px;
}

header nav ul li a {
  display: block;
  color: white;
  transition: all 0.25s ease-in-out;
}

header nav ul li:first-child a {
  font-size: 0;
}

header nav ul li.active a,
header nav ul li a:hover {
  color: var(--primary-color);
}

header nav button {
  display: none;
  position: absolute;
  width: 50px;
  height: 40px;
  top: 50%;
  margin-top: -20px;
  right: 20px;
  outline: none;
  background: none;
  border: none;
  cursor: pointer;
}

header nav button div {
  position: absolute;
  display: block;
  left: 0;
  right: 0;
  height: 6px;
  border-radius: 2px;
  background-color: white;
  transition: all 0.25s ease-in-out;
}

header nav button .top {
  top: 0;
  transform-origin: left center;
}

header nav.expanded button .top {
  transform: rotateZ(45deg);
  left: 11px;
  background-color: var(--primary-color);
}

header nav button .middle {
  top: 50%;
  margin-top: -3px;
  left: 15%;
  right: 15%;
  transform-origin: right center;
}

header nav.expanded button .middle {
  top: 0;
  left: 0;
  right: 11px;
  transform: rotateZ(-45deg);
  margin: 0;
  background-color: var(--primary-color);
}

header nav button .bottom {
  bottom: 0;
  left: 30%;
  right: 30%;
}

header nav.expanded button .bottom {
  opacity: 0;
}

@media (max-width: 768px) {
  header {
    display: block;
  }

  header nav ul {
    position: absolute;
    flex-flow: column nowrap;
    align-items: stretch;
    width: 100%;
    left: 0;
    top: 0;
    pointer-events: none;
  }

  header nav.expanded ul {
    pointer-events: auto;
  }

  header nav ul li:first-child {
    width: 50%;
  }

  header nav ul li:not(:first-child){
    margin: 0;
    transform: translateX(-100%);
    background-color: rgba(0,0,0,0.9);
    transition: transform 0.4s ease-in-out;
  }
    
  header nav ul li:not(:first-child) a{
    padding: 25px 15px;
  }

  header nav.expanded ul li:not(:first-child){
    transform: none;
  }

  header nav button {
    display: block;
  }
}