* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

ul {
  list-style: none;
}

header a {
  text-decoration: none;
  color: inherit;
}

button {
  border: none;
  background-color: transparent;
  cursor: pointer;
  color: inherit;
}

header {
  width: 100vw;
  position: fixed;
  top: 0;
  left: 0;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: 0.3s ease-in;
  padding: 20px 100px;
  z-index: 1;
  background: rgb(90, 42, 39);
  background: linear-gradient(180deg, #5a2a2780 0%, #5a2a274d 80%, #5a2a2700 100%);
}

/*header::after {
  content: "";
  background-image: url("https://static.igem.wiki/teams/5441/homepage/noise-texture.png");
  height: 300%;
  width: 300%;
  position: fixed;
  opacity: 0.1;
  z-index: 1;
  animation: 0.4s steps(2) infinite animate-grain;
}*/

@keyframes animate-grain {

  from {
    transform: translate(-5%, -10%);
  }

  to {
    transform: translate(-15%, -20%);
  }

}

header .logo {
  position: relative;
  font-weight: 700;
  color: var(--nav-color);
  font-family: logo, sans-serif;
  text-decoration: none;
  font-size: 2em;
  text-transform: uppercase;
  letter-spacing: 2px;
  z-index: 10;
}

header .logo img {
  width: 2em;
}

#hamburger {
  display: none;
  padding: 0.1rem;
  z-index: 10;
}

#hamburger div {
  background: var(--nav-color);
  width: 20px;
  height: 2px;
  margin-bottom: 4px;
  transition: 0.075s cubic-bezier(0.55, 0.055, 0.675, 0.19);

}

#hamburger :nth-child(1) {
  transition-duration: 0.075s;
  transition-timing-function: cubic-bezier(0.55, 0.055, 0.675, 0.19);
}

#hamburger :nth-child(2) {
  transition: opacity 0.075s ease;
}


#hamburger :nth-child(3) {
  transition: transform 0.075s cubic-bezier(0.55, 0.055, 0.675, 0.19);
}


#hamburger.active :nth-child(1) {
  transform: rotate(45deg) translate(4px, 4px);
  transition-delay: 0.12s;
  transition-timing-function: cubic-bezier(0.215, 0.61, 0.355, 1);
}

#hamburger.active :nth-child(2) {
  opacity: 0;
  transition: opacity 0.075s 0.12s ease;
}

#hamburger.active :nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
  transition: transform 0.075s 0.12s cubic-bezier(0.215, 0.61, 0.355, 1);
}

#scrolling-progress {
  background: var(--nav-sticky-color);
  height: 2px;
  border-radius: 0 1px 1px 0;
  position: absolute;
  top: 58px;
  left: 0;
  margin: 0;
  /* set it to invisible at first */
  visibility: hidden;
  opacity: 0;
  /* make it disappear immediately */
  transition: none;
}

.menu-bar {
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
  margin: auto 0;
  z-index: 10;
}

.menu-bar li {
  position: relative;
  list-style: none;
}

/* clickable links */
.menu-bar .nav-link {
  position: relative;
  margin: 0 15px;
  padding: 0;
  text-decoration: none;
  color: var(--nav-color);
  letter-spacing: 2px;
  font-family: header-link, sans-serif;
  font-size: 1rem;
  transition: .6s;
  cursor: pointer;
}

.menu-bar .nav-link:hover {
  text-shadow: 0 0 10px #fff, 0 0 20px #fff, 0 0 30px #A5978B;
}

/* link dropdowns */
.dropdown {
  display: flex;
  flex-direction: column;
  align-items: center;
  min-width: 150px;
  background: var(--nav-sticky-color);
  box-shadow: 3px 3px 10px black;
  position: absolute;
  top: 50px;
  left: 50%;
  z-index: 10;
  visibility: hidden;
  opacity: 0;
  transform: scale(0.97) translate(-50%, -10px);
  transition: 0.1s ease-in-out;
  padding: 10px;
}

.dropdown::after {
  content: "";
  position: absolute;
  height: calc(100% + 20px);
  width: 100%;
  top: -10px;
  left: 0;
  background: var(--nav-sticky-color);
  box-shadow: 3px 5px 10px black;
  z-index: -1;
  mask:
    url(https://static.igem.wiki/teams/5441/homepage/rip.svg) bottom,
    url(https://static.igem.wiki/teams/5441/homepage/rip-rotated.svg) top;
  mask-size: 200%;
  mask-composite: intersect;
}

.dropdown.active {
  visibility: visible;
  opacity: 1;
  transform: scale(1) translate(-50%, 10px);
}

.menu-bar li button span {
  transition: 0.2s;
}

.menu-bar li:has(.dropdown.active) button span {
  transform: rotate(180deg);
}

.dropdown-btn {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.15rem;
}

.dropdown-link {
  display: flex;
  padding: 0.3rem 0;
  transition: 0.1s ease-in-out;
  color: #281f1d;
  font-family: dropdown-link, sans-serif;
}

.dropdown-link:hover {
  text-shadow: 0 0 10px #fff, 0 0 20px #fff, 0 0 30px #A5978B;
  color: currentColor;
}

.dropdown-link::after {
  content: '';
  position: absolute;
  width: 100%;
  transform: scaleX(0);
  height: 2px;
  bottom: 5px;
  margin: 0 auto;
  background-color: #281f1d;
  transform-origin: bottom right;
  transition: transform 0.25s ease-out;
}

.dropdown-link:hover::after {
  transform: scaleX(1);
  transform-origin: bottom left;
}

/* navbar after scrolling */
header.sticky {
  padding: 5px 80px;
  background: var(--nav-sticky-bg);
  box-shadow: 0px 3px 10px black;
}

header.sticky::after {
  animation:
    1.5s ease-in-out forwards fade-out,
    0.4s steps(2) infinite animate-grain;
}

@keyframes fade-out {
  from {
    opacity: 0.1;
    visibility: visible;
  }

  to {
    opacity: 0;
    visibility: hidden;
  }
}

header.sticky .logo,
header.sticky .menu-bar .nav-link {
  color: var(--nav-sticky-color) !important;
}

header.sticky #hamburger div {
  color: var(--nav-sticky-color) !important;
}

header.sticky #scrolling-progress {
  /* make the transition occur with .3s delay when it appears*/
  transition: opacity .6s .3s ease-in-out;
  visibility: visible;
  opacity: 1;
}

/* responsive menu */
@media (max-width: 1200px) {
  :root {
    --nav-color: #eee;
    --nav-sticky-color: #eee;
    --nav-sticky-bg: #281f1d;
  }

  #hamburger {
    display: block;
  }

  header {
    padding: 20px 5vw;
  }

  header.sticky {
    padding: 5px 30px;
  }

  header.sticky #hamburger div {
    background: var(--nav-sticky-color);
  }

  .menu-bar {
    display: flex;
    flex-direction: column;
    align-items: stretch;
    row-gap: 1rem;
    padding: 1rem;
  }

  .menu-bar .nav-link {
    display: flex;
    justify-content: space-between;
    width: 100%;
    font-weight: 600;
    font-size: 1.2rem;
    margin: 0;
    color: var(--nav-bg-color) !important;
  }

  header.sticky .menu-bar .nav-link {
    color: var(--nav-bg-color) !important;
  }

  .menu-bar>li:not(:last-child) {
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--nav-sticky-bg);
  }

  nav {
    position: absolute;
    top: 80px;
    left: 0;
    min-height: 100vh;
    width: 100vw;
    z-index: 10;
    background: #e7e7e760;
    backdrop-filter: blur(2vw);
    -webkit-backdrop-filter: blur(2vw);
    visibility: hidden;
    opacity: 0;
    transform: scale(0.97) translateY(-10px);
    transition: 0.2s ease-in-out;
  }

  header.sticky nav {
    top: 50px;
  }

  .dropdown {
    min-width: 90%;
    position: static;
    top: 0;
    left: 0;
    background: none;
    box-shadow: none;
    display: none;
    transform: none !important;
  }

  .dropdown::after {
    display: none;
  }

  .dropdown-link {
    padding: 0.3rem 20px;
    font-size: 1.2rem;
  }

  .dropdown-link::after {
    display: none;
  }

  /* hamburger menu toggled on */
  nav.show {
    visibility: visible;
    opacity: 1;
    transform: scale(1) translateY(10px);
  }

  .dropdown.active {
    display: block;
  }

  header:has(nav.show) {
    background: var(--nav-sticky-bg);
  }

  header:has(nav.show)::after {
    background: none;
  }

  body:has(header nav.show) #topButton {
    transform: translateY(100px);
  }
}