/*
 * Layout System
 * Grid, spacing, section organization
 */

/* ============================================
   HEADER
   ============================================ */

.site-header {
  position: sticky;
  top: 0;
  background-color: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid rgba(44, 44, 44, 0.1);
  padding: var(--space-sm) var(--space-lg);
  z-index: 100;
}

.header-nav {
  display: flex;
  justify-content: flex-end;
  align-items: center;
  gap: var(--space-sm);
  max-width: var(--container-max-width);
  margin: 0 auto;
}

.header-nav__link {
  font-family: var(--font-primary);
  font-size: var(--font-size-caption);
  color: var(--color-text-secondary);
  letter-spacing: 0.02em;
  transition: color var(--transition-fast);
}

.header-nav__link:hover {
  color: var(--color-text-primary);
  opacity: 1;
}

.header-nav__link[aria-current="page"] {
  color: var(--color-text-primary);
}

.header-nav__separator {
  color: var(--color-text-secondary);
  font-size: var(--font-size-caption);
  opacity: 0.5;
}


/* ============================================
   SKIP LINK (Accessibility)
   ============================================ */

.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--color-charcoal);
  color: var(--color-white);
  padding: var(--space-sm) var(--space-md);
  z-index: 200;
  font-size: var(--font-size-small);
}

.skip-link:focus {
  top: 0;
}


/* ============================================
   MAIN SECTIONS
   ============================================ */

.section {
  padding: var(--section-padding-desktop) var(--space-lg);
}

.section:nth-child(even) {
  background-color: var(--color-background-secondary);
}

.section__container {
  max-width: var(--content-max-width);
  margin: 0 auto;
}

.section__heading {
  margin-bottom: var(--space-xl);
  text-align: left;
}

.section__content {
  /* Content flows naturally */
}


/* ============================================
   HERO SECTION
   ============================================ */

.hero {
  padding: var(--space-4xl) var(--space-lg);
  background-color: var(--color-background-primary);
}

.hero__container {
  max-width: var(--container-max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-3xl);
  align-items: center;
}

.hero__content {
  /* Content area */
}

.hero__headline {
  font-size: var(--font-size-h1);
  line-height: var(--line-height-tight);
  margin-bottom: var(--space-lg);
  color: var(--color-text-primary);
}

.hero__subheadline {
  font-family: var(--font-secondary);
  font-size: 1.25rem;
  line-height: var(--line-height-relaxed);
  color: var(--color-text-primary);
  margin-bottom: var(--space-md);
}

.hero__supporting {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
  margin-bottom: var(--space-xl);
}

.hero__cta {
  margin-top: var(--space-xl);
}

.hero__image {
  margin: 0;
}

.hero__image img {
  width: 100%;
  height: auto;
  border-radius: var(--radius-small);
}


/* ============================================
   DIAGRAMS & ILLUSTRATIONS
   ============================================ */

.section__diagram,
.section__illustration {
  margin: var(--space-3xl) 0;
}

.section__diagram img,
.section__illustration img {
  margin: 0 auto;
}


/* ============================================
   FILTERING SECTION (Special Layout)
   ============================================ */

.filtering__for,
.filtering__not-for {
  margin-bottom: var(--space-3xl);
}

.filtering__subheading {
  font-family: var(--font-primary);
  font-size: var(--font-size-h3);
  font-weight: var(--font-weight-semibold);
  color: var(--color-text-primary);
  margin-bottom: var(--space-md);
}

.filtering__not-for {
  padding-top: var(--space-xl);
  border-top: 1px solid rgba(44, 44, 44, 0.1);
}


/* ============================================
   CTA SECTION
   ============================================ */

.section--cta {
  text-align: center;
}

.cta__action {
  margin: var(--space-xl) 0;
}


/* ============================================
   FOOTER
   ============================================ */

.site-footer {
  background-color: var(--color-charcoal);
  color: rgba(255, 255, 255, 0.8);
  padding: var(--space-3xl) var(--space-lg);
}

.footer__container {
  max-width: var(--content-max-width);
  margin: 0 auto;
}

.footer__disclaimer {
  font-size: var(--font-size-small);
  line-height: var(--line-height-relaxed);
  margin-bottom: var(--space-lg);
}

.footer__legal {
  font-size: var(--font-size-caption);
  color: rgba(255, 255, 255, 0.5);
  padding-top: var(--space-md);
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}


/* ============================================
   RESPONSIVE LAYOUT
   ============================================ */

/* Tablet */
@media (max-width: 1023px) {
  .hero__container {
    grid-template-columns: 1fr;
    gap: var(--space-2xl);
  }
  
  .hero__image {
    order: -1; /* Image above content on smaller screens */
  }
}

/* Mobile */
@media (max-width: 767px) {
  .section {
    padding: var(--section-padding-mobile) var(--space-md);
  }
  
  .hero {
    padding: var(--space-2xl) var(--space-md);
  }
  
  .hero__container {
    gap: var(--space-xl);
  }
  
  .section__heading {
    margin-bottom: var(--space-lg);
  }
  
  .site-footer {
    padding: var(--space-2xl) var(--space-md);
  }
}