header {
  background: #6B7621;
  color: #FEF7E0;

  position: sticky;
  top: 0;
  z-index: 1000;

  --header-padding-y: 1rem;
  --header-padding-y-min: 0.5rem;
  --h1-size: 1.2rem;
  --h1-size-min: 0.9rem;
  --logo-width: 50px;
  --logo-width-min: 36px;
  --nav-font: 1.2rem;
  --nav-font-min: 1rem;

  /* allow smooth transitions when computed properties change */
  transition: padding 200ms ease, box-shadow 200ms ease, background 200ms ease;
  padding: calc(var(--header-padding-y) - (var(--header-padding-y) - var(--header-padding-y-min)) * var(--shrink, 0)) 2rem;
}

header.header--pinned {
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.25);
}

header .header-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 2rem;

  max-width: 1400px;
  margin: 0 auto;
}

header .header-logo {
  font-size: calc(var(--h1-size) - (var(--h1-size) - var(--h1-size-min)) * var(--shrink, 0));
  font-weight: 600;
  transition: font-size 180ms ease;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

header .header-logo img {
  width: calc(var(--logo-width) - (var(--logo-width) - var(--logo-width-min)) * var(--shrink, 0));
  height: auto;
  transition: width 180ms ease;
  object-fit: contain;
  display: block;
}

/* HAMBURGER (HIDDEN ON DESKTOP) */
header .hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: .5rem;
  z-index: 1100;
}

header .hamburger .bar {
  width: 25px;
  height: 2px;
  background: #FEF7E0;
  transition: all 0.3s ease;
}

header nav {
  display: flex;
  align-items: center;
  gap: 4rem;
}

header .nav__link {
  color: #FBC488;
  text-decoration: none;
  font-size: calc(var(--nav-font) - (var(--nav-font) - var(--nav-font-min)) * var(--shrink, 0));
  transition: font-size 180ms ease, padding 180ms ease, color 0.15s ease;
  padding: 0.25rem calc(0.4rem - 0.1rem * var(--shrink, 0));
}

header .nav__link:hover {
  color: #FEF7E0;
}

header .nav__link--active {
  color: #FEF7E0;
  border-bottom: 2px solid currentColor;
}

.nav-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100vh;

  background: rgba(0, 0, 0, 0.25);
  backdrop-filter: blur(4px);

  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
  z-index: 800;
  /* below the mobile menu but above everything else */
}

.nav-overlay.open {
  opacity: 1;
  pointer-events: auto;
}

@media (max-width: 800px) {
  header {
    --nav-font: 1.1rem;
    --nav-font-min: 0.95rem;
  }

  header nav {
    gap: 2.5rem;
  }
}

@media (max-width: 680px) {
  header .header-title {
    display: none;
  }

  header nav {
    gap: 2rem;
  }
}

@media (min-width: 481px) {
  .nav-overlay {
    display: none;
  }
}

@media (max-width: 480px) {
  header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
  }

  body.nav-menu-open {
    overflow: hidden;
  }

  header nav {
    position: absolute;
    left: 0;
    top: 100%;
    width: 100%;
    z-index: 900;

    display: flex;
    flex-direction: column;
    gap: 1.2rem;
    background: #6B7621;
    padding: 0 0 2rem 0;

    /* animation properties */
    max-height: 0;
    opacity: 0;
    overflow: hidden;

    transform: translateY(-40px);
    transition:
      max-height 0.8s ease,
      opacity 0.4s ease,
      transform 0.5s ease;
  }

  header nav.open {
    max-height: 500px;
    opacity: 1;
    transform: translateY(0);
  }

  header .hamburger {
    display: flex;
  }

  /* ANIMATE TO "X" */
  header .hamburger.active .bar:nth-child(1) {
    transform: rotate(45deg) translateY(10px);
  }

  header .hamburger.active .bar:nth-child(2) {
    opacity: 0;
  }

  header .hamburger.active .bar:nth-child(3) {
    transform: rotate(-45deg) translateY(-10px);
  }
}