/* ============================================
   Navigation & Theme Toggle
   ============================================ */

header {
  background: var(--surface-card);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border-bottom: 1px solid var(--border-glass);
  position: sticky;
  top: 0;
  z-index: 100;
}

header nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.logo a {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  color: var(--text-title);
}

.logo-icon {
  font-size: 1.5rem;
}

.logo-text {
  display: flex;
  align-items: baseline;
  gap: 0.4rem;
}

.brand-name {
  font-size: 1.125rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.brand-by {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.nav-links a {
  text-decoration: none;
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-body);
  transition: color 0.2s ease;
}

.nav-links a:hover {
  color: var(--accent);
}

.nav-links a.active {
  color: var(--accent);
}

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  color: var(--text-title);
  cursor: pointer;
  padding: 0.5rem;
}

.mobile-only {
  display: none;
}

@media (max-width: 768px) {
  .mobile-menu-btn {
    display: block;
  }

  .nav-links {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: var(--surface-card);
    backdrop-filter: blur(var(--glass-blur));
    -webkit-backdrop-filter: blur(var(--glass-blur));
    border-bottom: 1px solid var(--border-glass);
    padding: 1.5rem;
    gap: 1rem;
  }

  .nav-links.active {
    display: flex;
  }

  .nav-links a {
    width: 100%;
    padding: 0.5rem 0;
  }

  .mobile-only {
    display: flex;
  }

  .desktop-only {
    display: none;
  }
}

/* --- Theme Toggle --- */
.theme-toggle {
  background: var(--surface-overlay);
  border: 1px solid var(--border-glass);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--text-title);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.theme-toggle:hover {
  background: var(--surface-card);
  transform: scale(1.05);
}

.theme-toggle:active {
  transform: scale(0.95);
}

.theme-toggle svg {
  transition: opacity 0.3s ease, transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="light"] .theme-toggle .sun-icon {
  opacity: 1;
  transform: rotate(0deg) scale(1);
}

[data-theme="light"] .theme-toggle .moon-icon {
  opacity: 0;
  transform: rotate(90deg) scale(0.5);
  position: absolute;
}

[data-theme="dark"] .theme-toggle .sun-icon {
  opacity: 0;
  transform: rotate(-90deg) scale(0.5);
  position: absolute;
}

[data-theme="dark"] .theme-toggle .moon-icon {
  opacity: 1;
  transform: rotate(0deg) scale(1);
}