.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: var(--z-header);
  transition: var(--transition-base);
  background: transparent;
  pointer-events: none;
}

.header.scrolled {
  background: rgba(0, 0, 0, 0.92);
  backdrop-filter: blur(10px);
  pointer-events: auto;
}

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-5) var(--space-6);
  max-width: 1400px;
  margin: 0 auto;
}

.nav-logo {
  display: flex;
  align-items: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 1s ease-out;
}

.header.scrolled .nav-logo {
  opacity: 1;
  pointer-events: auto;
}

.nav-logo-img {
  filter: brightness(0) invert(1);
  opacity: 0.9;
  width: 100px;
  height: auto;
}

.nav-wave {
  font-family: Georgia, serif;
  font-size: 28px;
  color: var(--color-text-light);
  line-height: 1;
  opacity: 0.9;
  font-weight: 400;
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: var(--space-6);
  opacity: 0;
  pointer-events: none;
  transition: opacity 1s ease-out;
}

.header.scrolled .nav-menu {
  opacity: 1;
  pointer-events: auto;
}

.nav-link {
  color: var(--color-text-light);
  text-decoration: none;
  font-family: var(--font-sans);
  font-size: 13px;
  letter-spacing: 0.15em;
  position: relative;
  transition: var(--transition-base);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 0;
  height: 1px;
  background: var(--color-text-light);
  transition: var(--transition-base);
}

.nav-link:hover::after {
  width: 100%;
}

.menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  background: none;
  border: none;
  cursor: pointer;
  opacity: 0;
  pointer-events: none;
  transition: opacity 1s ease-out;
}

.header.scrolled .menu-toggle {
  opacity: 1;
  pointer-events: auto;
}

.menu-toggle span {
  width: 25px;
  height: 1px;
  background: var(--color-text-light);
  transition: var(--transition-base);
}

@media (max-width: 900px) {
  .nav-menu {
    position: fixed;
    top: 70px;
    left: -100%;
    width: 100%;
    height: calc(100vh - 70px);
    background: rgba(0, 0, 0, 0.95);
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: var(--space-6);
    transition: var(--transition-base);
  }

  .nav-menu.active {
    left: 0;
  }

  .menu-toggle {
    display: flex;
  }

  .menu-toggle.active span:nth-child(1) {
    transform: rotate(-45deg) translate(-5px, 6px);
  }
  .menu-toggle.active span:nth-child(2) {
    opacity: 0;
  }
  .menu-toggle.active span:nth-child(3) {
    transform: rotate(45deg) translate(-5px, -6px);
  }
}

/* ── Language Switch (v1.0) ── */
.lang-switch {
  display: flex;
  align-items: center;
  gap: 4px;
  margin-left: var(--space-6);
  opacity: 1;
  transition: opacity 1s ease-out;
}

.lang-btn {
  font-family: var(--font-sans);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--color-text-muted);
  background: none;
  border: none;
  cursor: pointer;
  padding: 0;
  transition: color var(--transition-fast);
}

.lang-btn:hover {
  color: var(--color-text-primary);
}

.lang-btn.active {
  color: var(--color-text-primary);
  font-weight: 500;
}

.lang-sep {
  color: var(--color-text-muted);
  font-size: 11px;
  user-select: none;
  opacity: 0.5;
}

@media (max-width: 900px) {
  .lang-switch {
    margin-left: auto;
    margin-right: var(--space-4);
    opacity: 1; /* mobile always visible */
  }
}

@media (max-width: 600px) {
  .navbar {
    padding: var(--space-3) var(--space-5);
  }
}