ese-website/_includes/header.css

header {
  z-index: 1000;
  display: flex;
  position: sticky;
  top: 0;
  padding: 2rem 0;
  backdrop-filter: blur(5px);
  -webkit-backdrop-filter: blur(5px);
  background-color: var(--color-background-header);
  box-shadow: 0 3px 15px hsla(0,0%,39.2%,.12);
}

.header-container {
  display: flex;
  justify-content: space-between;
}

@media (width >= 1024px) {
  .header-container {
    align-items: center;
  }
}

#header-logo img {
  max-height: 60px;
  display: block;
}

@media (width < 1024px) {
  header {
    padding: 1.5rem 0;
  }
  #header-logo img {
    max-height: 48px;
  }
}

#mainNav ul {
  margin: 0;
  padding: 0;
}

#mainNav li {
  display: inline-block;
  margin-left: 1.9rem;
}

.nav-item {
  position: relative;
  font-size: 16px;
  font-family: Aileron;
  font-weight: 500;
  line-height: 2;
  text-transform: uppercase;
  color: var(--color-text);
  text-decoration: none;
}

.nav-item::after {
  content: "";
  position: absolute;
  background: var(--color-primary);
  opacity: 0;
  bottom: -4px;
  left: 0;
  right: 0;
  height: 2px;
  transition: opacity .3s ease-out;
}

.nav-item-stream {
  color: var(--color-primary);
  font-family: Aileron;
  font-weight: 500;
  letter-spacing: 2px;
  text-decoration: none;
  text-transform: uppercase;
  transition: .2s ease-out;
  transition-property: color, background-color;
}

@media (width >= 1024px) {
  .nav-item:hover::after,
  .nav-item.active::after {
    opacity: 1;
  }
  .nav-item-stream {
    padding: .75rem 1.4rem;
    border: 2px solid var(--color-primary);
    border-radius: 3rem;
  }
  .nav-item-stream:hover {
    color: var(--color-button-active);
    background-color: var(--color-primary);
  }
}

#menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: .7rem;
  /* same height as logo */
  width: 48px;
  height: 48px;
}

#menu-toggle .icon {
  fill: var(--color-text);
  transition: fill .2s ease-out;
}

#mainNav.open #menu-toggle .icon,
#menu-toggle:hover .icon {
  fill: var(--color-primary);
}

#header-veil {
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  height: 100vh;
  background-color: rgba(0,0,0,.5);
  opacity: 0;
  transition: opacity .4s ease;
  pointer-events: none;
}

@media (width < 1024px) {
  #menu-toggle {
    display: block;
  }
  #mainNav {
    display: flex;
    flex-direction: column;
    align-items: end;
    overflow: hidden;
  }
  #mainNav ul {
    transition: .4s ease;
    transition-property: max-height, visibility;
    max-height: 0;
    visibility: hidden;
  }
  #mainNav.open ul {
    max-height: 100vh;
    visibility: visible;
    transition-property: max-height;
  }
  #mainNav li {
    display: block;
    text-align: right;
  }
  .nav-item,
  .nav-item-stream {
    padding: .7rem .7rem;
    display: block;
    transition: text-decoration-color .3s ease-out;
    text-decoration: 2px underline rgba(0,0,0,0);
  }
  .nav-item.active {
    color: var(--color-primary);
  }
  .nav-item:hover,
  .nav-item-stream:hover {
    text-decoration-color: var(--color-primary);
  }
  /* prevent page scrolling */
  .noscroll {
    overflow: hidden;
  }
  #header-veil:has(+ .header-container #mainNav.open) {
    opacity: 1;
    pointer-events: auto;
  }
}