/* =============================================================================
   LAYOUT
   Page shell: skip link, header, hero, page body (nav + main), footer.
   ============================================================================= */

/* --- Skip Link --- */

.skip-link {
  position: fixed;
  top: var(--space-3);
  left: var(--space-3);
  z-index: var(--z-skip-link);
  padding: var(--space-3) var(--space-5);
  background-color: var(--color-primary);
  color: var(--color-primary-text);
  font-weight: var(--font-weight-semibold);
  font-size: var(--text-sm);
  border-radius: var(--radius-lg);
  text-decoration: none;
  box-shadow: var(--shadow-lg);
  transform: translateY(calc(-100% - var(--space-6)));
  transition: transform var(--transition-fast);
}

.skip-link:focus-visible {
  transform: translateY(0);
  outline: var(--color-focus-ring);
  outline-offset: 3px;
}

/* --- Site Header --- */

.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  height: var(--header-height);
  background-color: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
  transition: background-color var(--transition-slow);
}

.site-header__inner {
  max-width: var(--page-max);
  margin-inline: auto;
  padding-inline: var(--page-padding);
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
}

.site-header__brand {
  display: flex;
  flex-direction: column;
  line-height: 1;
}

.site-header__eyebrow {
  font-size: var(--text-xs);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-muted);
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.site-header__title {
  font-size: var(--text-xl);
  font-weight: var(--font-weight-bold);
  color: var(--color-primary);
  letter-spacing: -0.02em;
}

.site-header__actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.site-header__portfolio-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  font-size: var(--text-sm);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-secondary);
  text-decoration: none;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-md);
  transition: color var(--transition-fast), background-color var(--transition-fast);
}

.site-header__portfolio-link:hover {
  color: var(--color-primary);
  background-color: var(--color-primary-light);
}

.site-header__portfolio-link:focus-visible {
  outline: var(--color-focus-ring);
  outline-offset: 3px;
}

/* --- Theme Toggle --- */

.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  background-color: var(--color-surface-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: background-color var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast);
  flex-shrink: 0;
}

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

.theme-toggle:focus-visible {
  outline: var(--color-focus-ring);
  outline-offset: 3px;
}

.theme-toggle__icon {
  position: absolute;
  transition: opacity var(--transition-fast), transform var(--transition-fast);
}

.theme-toggle__icon--moon {
  opacity: 0;
  transform: rotate(-90deg) scale(0.8);
}

[data-theme="dark"] .theme-toggle__icon--sun {
  opacity: 0;
  transform: rotate(90deg) scale(0.8);
}

[data-theme="dark"] .theme-toggle__icon--moon {
  opacity: 1;
  transform: rotate(0deg) scale(1);
}

/* --- Page Hero --- */

.page-hero {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
  color: var(--color-primary-text);
  padding: clamp(var(--space-12), 8vw, var(--space-24)) var(--page-padding);
}

.page-hero__inner {
  max-width: var(--content-max);
  margin-inline: auto;
}

.page-hero__label {
  font-size: var(--text-sm);
  font-weight: var(--font-weight-medium);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: rgb(255 255 255 / 0.75);
  margin-bottom: var(--space-3);
}

.page-hero__heading {
  font-size: clamp(var(--text-4xl), 6vw, var(--text-5xl));
  font-weight: var(--font-weight-bold);
  line-height: var(--leading-tight);
  letter-spacing: -0.03em;
  color: var(--color-primary-text);
  margin-bottom: var(--space-5);
}

.page-hero__description {
  font-size: clamp(var(--text-base), 2vw, var(--text-lg));
  line-height: var(--leading-relaxed);
  color: rgb(255 255 255 / 0.85);
  max-width: 40rem;
  margin-bottom: var(--space-8);
}

.page-hero__meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.hero-badge {
  display: inline-block;
  font-size: var(--text-xs);
  font-weight: var(--font-weight-semibold);
  letter-spacing: 0.05em;
  text-transform: uppercase;
  padding: var(--space-1) var(--space-3);
  background-color: rgb(255 255 255 / 0.15);
  border: 1px solid rgb(255 255 255 / 0.25);
  border-radius: var(--radius-full);
  color: var(--color-primary-text);
}

/* --- Page Body (two-column on wide screens) --- */

.page-body {
  max-width: var(--page-max);
  margin-inline: auto;
  padding-inline: var(--page-padding);
  padding-block: var(--space-12);
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-8);
}

@media (min-width: 72em) {
  .page-body {
    grid-template-columns: var(--nav-width) 1fr;
    align-items: start;
    gap: var(--space-12);
  }
}

/* --- Demo Navigation (in-page sidebar) --- */

.demo-nav {
  position: sticky;
  top: var(--header-height);
  z-index: 50;
  background-color: var(--color-bg);
  padding-bottom: var(--space-2);
}

.demo-nav__mobile {
  /* Details/summary on mobile */
}

.demo-nav__mobile-summary {
  font-weight: var(--font-weight-semibold);
  font-size: var(--text-sm);
  padding: var(--space-3) var(--space-4);
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  color: var(--color-text);
}

.demo-nav__list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.demo-nav__mobile .demo-nav__list {
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  z-index: 100;
  border: 1px solid var(--color-border);
  border-top: none;
  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
  background-color: var(--color-surface);
  padding: var(--space-2) 0;
}

.demo-nav__list--desktop {
  display: none;
}

.demo-nav__link {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-secondary);
  text-decoration: none;
  border-radius: var(--radius-md);
  transition: color var(--transition-fast), background-color var(--transition-fast);
  white-space: nowrap;
}

.demo-nav__link:hover {
  color: var(--color-primary);
  background-color: var(--color-primary-light);
}

.demo-nav__link:focus-visible {
  outline: var(--color-focus-ring);
  outline-offset: 2px;
}

.demo-nav__link.is-active {
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  font-weight: var(--font-weight-semibold);
}

.demo-nav__num {
  font-size: var(--text-xs);
  font-family: var(--font-mono);
  color: var(--color-text-muted);
  min-width: 1.75rem;
}

@media (min-width: 72em) {
  .demo-nav__mobile {
    display: none;
  }

  .demo-nav {
    top: calc(var(--header-height) + var(--space-6));
    align-self: start;
    z-index: auto;
    padding-bottom: 0;
  }

  .demo-nav__list--desktop {
    display: block;
    padding: var(--space-2) 0;
  }

  .demo-nav__link {
    padding: var(--space-2) var(--space-3);
    border-radius: var(--radius-md);
  }
}

/* --- Demo Main --- */

.demo-main {
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-16);
}

/* --- Site Footer --- */

.site-footer {
  background-color: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding-block: var(--space-10);
  margin-top: var(--space-16);
}

.site-footer__inner {
  max-width: var(--page-max);
  margin-inline: auto;
  padding-inline: var(--page-padding);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-3);
  text-align: center;
}

.site-footer__credit {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
}

.site-footer__links {
  display: flex;
  gap: var(--space-6);
  font-size: var(--text-sm);
}

.site-footer__links a {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  color: var(--color-text-secondary);
}

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

.site-footer__tech {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  font-family: var(--font-mono);
}

/* --- Print styles --- */

@media print {
  .site-header,
  .demo-nav,
  .theme-toggle,
  .site-footer__links {
    display: none;
  }

  .page-hero {
    background: none;
    color: #000;
    padding: 1rem 0;
  }

  .page-body {
    grid-template-columns: 1fr;
    padding: 0;
  }

  .demo-section {
    page-break-inside: avoid;
  }

  details {
    border: none;
  }

  details[open] .demo-code__body,
  details .demo-code__body {
    display: block;
  }
}