/* Header */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  padding-top: env(safe-area-inset-top, 0);
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-border);
  z-index: var(--z-sticky);
  transition: box-shadow var(--transition-base);
  will-change: transform;
}

.header.scrolled {
  box-shadow: var(--shadow-md);
}

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

/* Logo */
.logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: var(--text-xl);
  font-weight: var(--weight-bold);
  color: var(--color-text);
  text-decoration: none;
}

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

.logo__icon {
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: var(--weight-bold);
  font-size: var(--text-sm);
}

/* Nav */
.nav,
.nav-desktop {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.nav-desktop__list {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  list-style: none;
  padding: 0;
  margin: 0;
}

.nav__link,
.nav-desktop__link {
  padding: var(--space-sm) var(--space-md);
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  color: var(--color-text-secondary);
  text-decoration: none;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  position: relative;
}

.nav__link::after,
.nav-desktop__link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: var(--space-md);
  right: var(--space-md);
  height: 2px;
  background: var(--color-primary);
  border-radius: 1px;
  transform: scaleX(0);
  transition: transform var(--transition-base);
}

.nav__link:hover,
.nav-desktop__link:hover {
  color: var(--color-primary);
}

.nav__link:hover::after,
.nav__link.active::after,
.nav-desktop__link:hover::after,
.nav-desktop__link.active::after {
  transform: scaleX(1);
}

.nav__link.active,
.nav-desktop__link.active {
  color: var(--color-primary);
}

/* Theme toggle */
.theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-sm);
  border-radius: var(--radius-md);
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
}

.theme-toggle:hover {
  background: var(--color-border-light);
  color: var(--color-text);
}

.theme-toggle__icon {
  width: 20px;
  height: 20px;
}

/* Show/hide icons based on theme */
.theme-toggle__icon--sun { display: none; }
.theme-toggle__icon--moon { display: block; }
[data-theme="dark"] .theme-toggle__icon--sun { display: block; }
[data-theme="dark"] .theme-toggle__icon--moon { display: none; }

/* Mobile menu button */
.menu-toggle,
.hamburger {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-sm);
  color: var(--color-text);
}

.menu-toggle__bar,
.hamburger__line {
  display: block;
  width: 24px;
  height: 2px;
  background: currentColor;
  margin: 5px 0;
  border-radius: 2px;
  transition: all var(--transition-base);
}

.menu-toggle.active .menu-toggle__bar:nth-child(1),
.hamburger.active .hamburger__line:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.menu-toggle.active .menu-toggle__bar:nth-child(2),
.hamburger.active .hamburger__line:nth-child(2) {
  opacity: 0;
}

.menu-toggle.active .menu-toggle__bar:nth-child(3),
.hamburger.active .hamburger__line:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* Mobile nav */
.mobile-nav {
  display: none;
  position: fixed;
  top: var(--header-height);
  left: 0;
  right: 0;
  bottom: 0;
  height: calc(100vh - var(--header-height));
  height: calc(100dvh - var(--header-height));
  background: var(--color-surface);
  z-index: var(--z-dropdown);
  padding: var(--space-lg);
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  transform: translateX(100%);
  transition: transform var(--transition-base);
}

.mobile-nav.active {
  transform: translateX(0);
}

.mobile-nav__link {
  display: block;
  padding: var(--space-md);
  font-size: var(--text-lg);
  font-weight: var(--weight-medium);
  color: var(--color-text);
  text-decoration: none;
  border-radius: var(--radius-md);
  transition: background var(--transition-fast);
  min-height: var(--touch-target-min);
  display: flex;
  align-items: center;
}

.mobile-nav__link:hover,
.mobile-nav__link.active {
  background: var(--color-primary-bg);
  color: var(--color-primary);
}

@media (max-width: 768px) {
  .nav,
  .nav-desktop {
    display: none;
  }

  .menu-toggle,
  .hamburger {
    display: block;
  }

  .mobile-nav {
    display: block;
  }

  body {
    padding-bottom: calc(56px + env(safe-area-inset-bottom, 0));
  }
}

/* ===== Bottom Navigation Bar (Mobile Only) ===== */

.bottom-nav {
  display: none;
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  z-index: var(--z-sticky);
  padding-bottom: env(safe-area-inset-bottom, 0);
}

@media (max-width: 768px) {
  .bottom-nav {
    display: flex;
    justify-content: space-around;
    align-items: center;
    height: calc(56px + env(safe-area-inset-bottom, 0));
  }
}

.bottom-nav__item {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2px;
  padding: var(--space-xs) var(--space-sm);
  min-width: 56px;
  min-height: 48px;
  color: var(--color-text-muted);
  text-decoration: none;
  font-size: 10px;
  font-weight: var(--weight-medium);
  transition: color var(--transition-fast);
  -webkit-tap-highlight-color: transparent;
}

.bottom-nav__item.active {
  color: var(--color-primary);
}

.bottom-nav__item:active {
  color: var(--color-primary);
}

.bottom-nav__icon {
  width: 24px;
  height: 24px;
}

/* Breadcrumbs */
.breadcrumbs {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  margin-bottom: var(--space-xl);
  flex-wrap: wrap;
}

.breadcrumbs a {
  color: var(--color-text-muted);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.breadcrumbs a:hover {
  color: var(--color-primary);
}

@media (max-width: 768px) {
  .breadcrumbs a {
    padding: var(--space-xs) var(--space-sm);
    min-height: var(--touch-target-min);
    display: inline-flex;
    align-items: center;
  }
}

.breadcrumbs__sep {
  color: var(--color-border);
  margin: 0 2px;
}

.breadcrumbs__current {
  color: var(--color-text);
  font-weight: var(--weight-medium);
}

/* Reading progress bar */
.reading-progress {
  position: fixed;
  top: var(--header-height);
  left: 0;
  width: 0%;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  z-index: var(--z-sticky);
  transition: width 100ms linear;
}

/* Footer */
.footer {
  background: linear-gradient(180deg, #1e293b 0%, #0f172a 100%);
  color: rgba(255, 255, 255, 0.8);
  padding: var(--space-4xl) 0 var(--space-2xl);
  margin-top: var(--space-3xl);
  position: relative;
}

.footer::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent), var(--color-purple));
}

.footer a {
  color: rgba(255, 255, 255, 0.8);
  transition: color var(--transition-fast), transform var(--transition-fast);
}

.footer a:hover {
  color: white;
}

.footer__grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-2xl);
  margin-bottom: var(--space-2xl);
}

.footer__title,
.footer__col-title {
  color: white;
  font-size: var(--text-sm);
  font-weight: var(--weight-semibold);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-md);
}

.footer__tagline {
  font-size: var(--text-sm);
  color: rgba(255, 255, 255, 0.6);
  max-width: 280px;
  margin-top: var(--space-md);
  line-height: var(--leading-relaxed);
}

.footer__links {
  list-style: none;
  padding: 0;
}

.footer__links li {
  margin-bottom: var(--space-sm);
  color: inherit;
}

.footer__links a {
  font-size: var(--text-sm);
  display: inline-block;
}

.footer__links a:hover {
  transform: translateX(4px);
}

.footer__bottom {
  margin-top: var(--space-xl);
  padding-top: var(--space-xl);
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  font-size: var(--text-sm);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer__disclaimer {
  font-size: var(--text-xs);
  opacity: 0.5;
  max-width: 600px;
  line-height: var(--leading-relaxed);
}

@media (max-width: 768px) {
  .footer__grid {
    grid-template-columns: 1fr;
    gap: var(--space-xl);
  }

  .footer__bottom {
    flex-direction: column;
    gap: var(--space-md);
    text-align: center;
  }

  .footer {
    padding-bottom: calc(var(--space-2xl) + 56px + env(safe-area-inset-bottom, 0));
  }
}