.site-header{
  position:fixed;
  inset:0 0 auto;
  z-index:300;
  color:var(--color-white);
  transition:background-color .3s ease,color .3s ease,box-shadow .3s ease;
}

.site-header.scrolled{
  color:var(--color-deep);
  background:rgba(255,255,255,.96);
  box-shadow:0 8px 30px rgba(10,45,55,.06);
}

.nav{
  display:grid;
  grid-template-columns:auto 1fr;
  align-items:center;
  gap:32px;
  padding-block:var(--nav-pad-y);
}

.logo{
  display:block;
  width:var(--logo-width);
  line-height:0;
}

.logo-img{
  display:block;
  width:100%;
  height:auto;
  object-fit:contain;
}

.logo-white{display:block}
.logo-dark{display:none}
.site-header.scrolled .logo-white{display:none}
.site-header.scrolled .logo-dark{display:block}

/* Navigation */
.nav-menu{
  justify-self:end;
}

.nav-list{
  display:flex;
  align-items:center;
  gap:34px;
}

.nav-list li{
  display:block;
}

.nav-link{
  position:relative;
  display:inline-flex;
  align-items:center;
  justify-content:center;
  min-height:40px;
  font-size:var(--text-xs);
  font-weight:var(--weight-semibold);
  letter-spacing:.13em;
  color:inherit;
}

.nav-link:not(.nav-book)::after{
  content:"";
  position:absolute;
  left:0;
  right:100%;
  bottom:3px;
  height:1px;
  background:currentColor;
  transition:right .25s ease;
}

.nav-link:not(.nav-book):hover::after{
  right:0;
}

.site-header:not(.scrolled) .nav-link:not(.nav-book){
  color:var(--color-white);
}

.site-header.scrolled .nav-link:not(.nav-book){
  color:var(--color-deep);
}

/* Same nav item, only visual modifier */
.nav-book{
  padding-inline:18px;
  border-radius:var(--radius-sm);
  background:var(--color-red);
  color:var(--color-white);
}

.nav-book:hover,
.nav-book:visited{
  color:var(--color-white);
}

/* Menu toggle */
.menu-btn{
  display:none;
  width:44px;
  height:44px;
  border:0;
  background:transparent;
  padding:10px 0 10px 12px;
  color:inherit;
}

.menu-btn span{
  display:block;
  height:1px;
  margin:7px 0;
  background:currentColor;
}

@media(max-width:900px){
  .nav{
    position:relative;
    grid-template-columns:44px 1fr 44px;
    gap:0;
    padding-block:var(--nav-pad-y-mobile);
  }

  .logo{
    grid-column:2;
    justify-self:center;
    width:var(--logo-width-mobile);
  }

  .menu-btn{
    display:block;
    grid-column:3;
    justify-self:end;
  }

  .nav-menu{
    position:fixed;
    top:var(--mobile-header-height,72px);
    left:0;
    right:0;
    width:100%;
    display:none;
    background:rgba(255,255,255,.98);
    color:var(--color-deep);
    box-shadow:0 18px 35px rgba(0,0,0,.08);
  }

  .nav-menu.open{
    display:block;
  }

  .nav-list{
    display:flex;
    flex-direction:column;
    align-items:stretch;
    gap:0;
    width:100%;
   /*padding:10px 0 18px;*/
  }

  .nav-list li{
    width:100%;
  }

  .nav-link{
    width:100%;
    min-height:0;
    justify-content:flex-start;
    padding:16px var(--page-pad);
    color:var(--color-deep);
  }

  /* Mobile menu has a white background, so links must stay dark
     regardless of the header's transparent/scrolled state. */
  .site-header:not(.scrolled) .nav-menu .nav-link:not(.nav-book),
  .site-header.scrolled .nav-menu .nav-link:not(.nav-book){
    color:var(--color-deep);
  }

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

  .nav-book{
    margin:0;
    border-radius:0;
    background:var(--color-red);
    color:var(--color-white);
  }

  .nav-book,
  .nav-book:visited{
    color:var(--color-white);
  }

  .site-header:not(.scrolled) .menu-btn span{
    background:var(--color-white);
  }

  .site-header.scrolled .menu-btn span{
    background:var(--color-deep);
  }
}


/* Layering: navigation must always stay above the GO7 iframe. */
.site-header{
  z-index:300;
}

@media(max-width:900px){
  .nav-menu{
    z-index:310;
  }
}