/* ============================================
   Header Styles - Refined & Minimal
   ============================================ */

.site-header {
  position: sticky;
  top: 0;
  z-index: 99;
  background: rgba(250, 250, 250, 0.8);
  border-bottom: 1px solid var(--color-border);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] .site-header {
  background: rgba(10, 10, 10, 0.8);
}

.header-container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.site-logo {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-text);
  text-decoration: none;
  transition: all 0.2s ease;
  letter-spacing: -0.02em;
}

.site-logo:hover {
  color: var(--color-accent);
  transform: translateY(-1px);
}

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

.nav-links {
  display: flex;
  gap: 2rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-links a {
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: all 0.2s ease;
  font-size: 0.95rem;
  font-weight: 500;
  position: relative;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--color-accent);
  transition: width 0.3s ease;
}

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

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

.theme-toggle {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 50%;
  cursor: pointer;
  padding: 0.5rem;
  color: var(--color-text-secondary);
  font-size: 1.25rem;
  transition: all 0.2s ease;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
}

.theme-toggle:hover {
  background: var(--color-accent);
  color: white;
  border-color: var(--color-accent);
  transform: rotate(180deg) scale(1.05);
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  color: var(--color-text);
}

.mobile-menu-toggle svg {
  width: 24px;
  height: 24px;
}

/* Responsive Design */
@media (max-width: 768px) {
  .header-container {
    padding: 1rem;
  }
  
  .site-logo {
    font-size: 1.25rem;
  }
  
  .nav-links {
    position: fixed;
    top: 60px;
    left: 0;
    right: 0;
    background: var(--color-surface);
    flex-direction: column;
    padding: 1rem;
    gap: 1rem;
    border-bottom: 1px solid var(--color-border);
    transform: translateY(-100%);
    opacity: 0;
    transition: all 0.3s ease;
    pointer-events: none;
  }
  
  .nav-links.active {
    transform: translateY(0);
    opacity: 1;
    pointer-events: all;
  }
  
  .mobile-menu-toggle {
    display: block;
  }
  
  .header-nav {
    gap: 1rem;
  }
}

@media (max-width: 480px) {
  .header-container {
    padding: 0.75rem;
  }
  
  .site-logo {
    font-size: 1.1rem;
  }
  
  .theme-toggle {
    width: 36px;
    height: 36px;
    font-size: 1.1rem;
  }
}