/**
 * Core Layout, Header & Footer Architecture
 */

/* Skip Link */
.skip-link {
  position: absolute;
  top: -100px;
  left: 20px;
  background: var(--color-accent);
  color: #000;
  padding: 12px 20px;
  font-weight: 600;
  z-index: 9999;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 20px;
}

/* Site Container */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-md);
}

.container-narrow {
  width: 100%;
  max-width: var(--max-width-narrow);
  margin: 0 auto;
  padding: 0 var(--space-md);
}

/* Header & Navigation */
.site-header {
  position: sticky;
  top: 0;
  width: 100%;
  height: var(--header-height);
  background: rgba(10, 10, 10, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  z-index: 1000;
  display: flex;
  align-items: center;
  transition: background var(--transition-normal), border-color var(--transition-normal);
}

.nav-wrapper {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
}

.brand {
  display: flex;
  align-items: baseline;
  gap: var(--space-xs);
}

.brand-title {
  font-family: var(--font-serif);
  font-size: 1.75rem;
  font-weight: 400;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-text-primary);
}

.brand-subtitle {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--color-text-muted);
}

.main-nav {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}

.nav-link {
  font-size: 0.875rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-text-secondary);
  position: relative;
  padding: var(--space-xs) 0;
  transition: color var(--transition-fast);
}

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

.nav-link.active {
  color: var(--color-text-primary);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 1px;
  background-color: var(--color-accent);
}

/* Mobile Nav Toggle */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: space-around;
  width: 28px;
  height: 24px;
  background: transparent;
  border: none;
  padding: 0;
  z-index: 1010;
}

.mobile-menu-toggle span {
  width: 100%;
  height: 2px;
  background: var(--color-text-primary);
  transition: transform var(--transition-fast), opacity var(--transition-fast);
  transform-origin: center;
}

.mobile-menu-toggle.open span:nth-child(1) {
  transform: translateY(8px) rotate(45deg);
}

.mobile-menu-toggle.open span:nth-child(2) {
  opacity: 0;
}

.mobile-menu-toggle.open span:nth-child(3) {
  transform: translateY(-8px) rotate(-45deg);
}

/* Main SPA Host */
#app-root {
  flex: 1 0 auto;
  position: relative;
  min-height: calc(100vh - var(--header-height) - 140px);
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--color-border-light);
  background: var(--color-bg-secondary);
  padding: var(--space-2xl) 0 var(--space-xl);
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

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

.footer-brand h3 {
  font-size: 1.5rem;
  color: var(--color-text-primary);
  margin-bottom: var(--space-xs);
}

.footer-brand p {
  color: var(--color-text-secondary);
  max-width: 420px;
  line-height: 1.6;
}

.footer-col h4 {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--color-text-primary);
  margin-bottom: var(--space-md);
}

.footer-col ul {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.footer-col a:hover {
  color: var(--color-accent);
}

.footer-bottom {
  display: flex;
  justify-content: center;
  align-items: center;
  padding-top: var(--space-lg);
  border-top: 1px solid var(--color-border-subtle);
  font-size: 0.75rem;
}

.footer-copyright {
  width: 100%;
  text-align: center;
  margin: 0 auto;
}

/* Responsive Queries */
@media (max-width: 900px) {
  :root {
    --header-height: 60px;
    --combined-header-height: 155px;
  }

  .mobile-menu-toggle {
    display: flex;
  }

  .main-nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    width: 100%;
    height: calc(100vh - var(--header-height));
    background: var(--color-bg);
    flex-direction: column;
    justify-content: flex-start;
    padding: var(--space-2xl) var(--space-md);
    gap: var(--space-xl);
    transform: translateY(-100%);
    opacity: 0;
    pointer-events: none;
    transition: transform var(--transition-normal), opacity var(--transition-normal);
    z-index: 1100;
  }

  .main-nav.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  .nav-links {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-md);
  }

  .nav-link {
    font-size: 1.25rem;
  }

  .footer-inner {
    grid-template-columns: 1fr;
    gap: var(--space-xl);
  }

  .footer-bottom {
    flex-direction: column;
    gap: var(--space-sm);
    text-align: center;
  }
}