/* ============================================
   EDUVAULT - Header / Navigation
   ============================================ */

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-primary);
  z-index: var(--z-sticky);
  transition: all var(--transition-base);
}

.site-header.scrolled {
  background: rgba(255, 255, 255, 0.95);
  box-shadow: var(--shadow-md);
}

.header-inner {
  max-width: var(--container-wide);
  margin: 0 auto;
  padding: 0 var(--space-6);
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-8);
}

/* Logo */
.logo {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-family: var(--font-display);
  font-weight: var(--fw-extrabold);
  font-size: var(--fs-xl);
  color: var(--text-primary);
  flex-shrink: 0;
}

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

.logo-icon {
  width: 38px;
  height: 38px;
  background: var(--accent-gradient);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--fs-lg);
  color: var(--text-on-accent);
}

.logo span {
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-primary-hover));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* Search Bar */
.header-search {
  flex: 1;
  max-width: 480px;
  position: relative;
}

.header-search i {
  position: absolute;
  left: var(--space-4);
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-tertiary);
  font-size: var(--fs-sm);
}

.header-search input {
  width: 100%;
  padding: var(--space-3) var(--space-4) var(--space-3) var(--space-10);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-full);
  color: var(--text-primary);
  font-size: var(--fs-sm);
  transition: all var(--transition-base);
}

.header-search input::placeholder {
  color: var(--text-tertiary);
}

.header-search input:focus {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px var(--accent-primary-muted);
  background: var(--bg-secondary);
}

/* Navigation */
.main-nav {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.nav-link {
  padding: var(--space-2) var(--space-4);
  font-size: var(--fs-sm);
  font-weight: var(--fw-medium);
  color: var(--text-secondary);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  position: relative;
  white-space: nowrap;
}

.nav-link:hover, .nav-link.active {
  color: var(--text-primary);
  background: var(--bg-tertiary);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 50%;
  transform: translateX(-50%);
  width: 20px;
  height: 2px;
  background: var(--accent-primary);
  border-radius: var(--radius-full);
}

/* Header Actions */
.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  flex-shrink: 0;
}

.header-actions .btn-icon {
  width: 40px;
  height: 40px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-secondary);
  font-size: var(--fs-base);
  transition: all var(--transition-fast);
  position: relative;
}

.header-actions .btn-icon:hover {
  background: var(--bg-card-hover);
  color: var(--text-primary);
  border-color: var(--border-secondary);
}

.notification-dot {
  position: absolute;
  top: 8px;
  right: 8px;
  width: 8px;
  height: 8px;
  background: var(--accent-primary);
  border-radius: var(--radius-full);
  border: 2px solid var(--bg-tertiary);
}

.header-avatar {
  width: 38px;
  height: 38px;
  border-radius: var(--radius-full);
  background: linear-gradient(135deg, var(--accent-primary-muted), var(--accent-blue-muted));
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: var(--fw-bold);
  font-size: var(--fs-sm);
  color: var(--accent-primary);
  cursor: pointer;
  border: 2px solid var(--border-primary);
  transition: all var(--transition-fast);
}

.header-avatar:hover {
  border-color: var(--accent-primary);
  box-shadow: 0 0 12px var(--accent-primary-glow);
}

/* Mobile Menu Toggle */
.mobile-toggle {
  display: none;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
  font-size: var(--fs-lg);
  color: var(--text-primary);
  cursor: pointer;
}

/* Mobile Nav Overlay */
.mobile-nav-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--bg-overlay);
  z-index: var(--z-overlay);
  opacity: 0;
  transition: opacity var(--transition-base);
}

.mobile-nav-overlay.active {
  opacity: 1;
}

.mobile-nav {
  display: none;
  position: fixed;
  top: 0;
  right: -300px;
  width: 300px;
  height: 100vh;
  background: var(--bg-secondary);
  border-left: 1px solid var(--border-primary);
  z-index: var(--z-modal);
  padding: var(--space-6);
  transition: right var(--transition-base);
  overflow-y: auto;
}

.mobile-nav.active {
  right: 0;
}

.mobile-nav-close {
  display: flex;
  justify-content: flex-end;
  margin-bottom: var(--space-8);
}

.mobile-nav .nav-link {
  display: block;
  padding: var(--space-3) var(--space-4);
  font-size: var(--fs-base);
  margin-bottom: var(--space-1);
}

.mobile-nav-actions {
  margin-top: var(--space-8);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.mobile-nav-actions .btn {
  width: 100%;
  justify-content: center;
}

/* ── Responsive ── */
@media (max-width: 1024px) {
  .header-search {
    display: none;
  }
}

@media (max-width: 768px) {
  .main-nav {
    display: none;
  }
  
  .header-actions .btn {
    display: none;
  }
  
  .mobile-toggle {
    display: flex;
  }
  
  .mobile-nav, .mobile-nav-overlay {
    display: block;
  }
}