/* Header & Navigation */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  width: 100%;
  z-index: 100;
  backdrop-filter: blur(12px);
  background: rgba(15,17,21,.7);
  border-bottom: 1px solid rgba(255,255,255,.06);
  transform: translateY(-100%);
  opacity: 0;
  transition: transform .4s cubic-bezier(.4,0,.2,1), opacity .35s ease;
}
.site-header.nav-visible  { transform: translateY(0); opacity: 1; }
.site-header.nav-instant  { transition: none !important; }
.navbar { display:flex; align-items:center; justify-content:space-between; gap:2rem; padding:.9rem 1.25rem; max-width:var(--container-max); margin-inline:auto; }
.navbar .brand { font-weight:700; font-size:1.05rem; letter-spacing:.5px; display:flex; align-items:center; gap:.6rem; color:var(--color-text); }
.navbar .brand span { background:var(--gradient-accent); -webkit-background-clip:text; background-clip:text; color:transparent; }
.nav-links { list-style:none; display:flex; gap:.5rem; margin:0; padding:0; align-items:center; }
.nav-links a { display:block; padding:.55rem .95rem; font-size:.85rem; font-weight:500; color:var(--color-text-dim); border-radius:var(--radius-ui); transition: color var(--transition-fast), background var(--transition-fast); }
.nav-links a:hover, .nav-links a:focus-visible { background:var(--color-bg-alt); color:var(--color-accent); text-decoration:none; }
.nav-links a.active { background: var(--color-accent); color:#fff; border-radius:var(--radius-ui); }

/* Language switcher */
.lang-switcher { 
  display:flex; 
  align-items:center; 
  gap:.2rem; 
  margin-left:.5rem; 
  background:var(--color-bg-alt); 
  border-radius:var(--radius-ui); 
  padding:.25rem; 
}
.lang-btn { 
  background:transparent; 
  border:none; 
  color:var(--color-text-dim); 
  font-size:.8rem; 
  font-weight:600; 
  padding:.35rem .65rem; 
  border-radius:calc(var(--radius-ui) - 2px); 
  cursor:pointer; 
  transition: all .2s ease; 
  letter-spacing:.3px;
}
.lang-btn:hover { 
  color:var(--color-text); 
}
.lang-btn.active { 
  background:var(--color-accent); 
  color:#fff; 
  box-shadow:0 2px 4px rgba(0,0,0,.2);
}
.lang-divider { 
  display:none; 
}

/* Mobile menu */
.nav-toggle { display:inline-flex; flex-direction:column; justify-content:center; gap:5px; width:40px; height:40px; border-radius:var(--radius-md); border:1px solid var(--color-border); background:var(--color-surface); color:var(--color-text); box-shadow:var(--shadow-sm); position:relative; }
.nav-toggle span { width:18px; height:2px; background:currentColor; border-radius:2px; margin-inline:auto; transition: transform var(--transition-med), opacity var(--transition-fast); }
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity:0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

@media (max-width: 820px) {
  .nav-links-wrapper { 
    position:absolute; 
    left:0; right:0; top:100%; 
    background: rgba(15,17,21,.94); 
    backdrop-filter: blur(14px); 
    border-bottom:1px solid rgba(255,255,255,.07); 
    display:block; 
    max-height:0; 
    overflow:hidden; 
    opacity:0; 
    transform: translateY(-6px); 
    transition: max-height .45s cubic-bezier(.4,0,.2,1), opacity .3s ease, transform .45s cubic-bezier(.4,0,.2,1);
  }
  .nav-links-wrapper.open { 
    max-height:420px; 
    opacity:1; 
    transform: translateY(0); 
  }
  .nav-links { flex-direction:column; padding: .75rem 1rem 1.25rem; }
  .nav-links a { font-size:.95rem; }
  .nav-links.show { display:flex; }
  .nav-toggle { display:flex; }
}
@media (min-width: 821px) { .nav-toggle { display:none; } }