/* ============================================================
   layout.css — Page shell, sidebar navigation, responsive grid
   ============================================================ */

/* ---- App shell ---- */
.app-shell {
  display: flex;
  min-height: 100vh;
}

/* ---- Sidebar navigation ---- */
.sidebar {
  width: var(--nav-width);
  min-height: 100vh;
  background: var(--color-navy);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0;
  left: 0;
  z-index: var(--z-nav);
  overflow-y: auto;
  transition: transform var(--transition-normal);
}

.sidebar__brand {
  padding: var(--space-6) var(--space-6) var(--space-4);
  border-bottom: 1px solid var(--color-navy-light);
}

.sidebar__logo {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  text-decoration: none;
}

.sidebar__logo-icon {
  font-size: 1.75rem;
  line-height: 1;
}

.sidebar__logo-text {
  display: flex;
  flex-direction: column;
}

.sidebar__logo-title {
  font-size: var(--text-xl);
  font-weight: var(--weight-bold);
  color: var(--text-inverse);
  letter-spacing: -0.01em;
}

.sidebar__logo-sub {
  font-size: var(--text-xs);
  color: rgba(255,255,255,0.55);
  font-weight: var(--weight-regular);
  line-height: 1.4;
}

.sidebar__nav {
  flex: 1;
  padding: var(--space-4) 0;
}

.sidebar__section-label {
  font-size: var(--text-xs);
  font-weight: var(--weight-semi);
  color: rgba(255,255,255,0.35);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  padding: var(--space-4) var(--space-6) var(--space-2);
}

.nav-item {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-6);
  color: rgba(255,255,255,0.72);
  text-decoration: none;
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  transition: background var(--transition-fast), color var(--transition-fast);
  border-left: 3px solid transparent;
}

.nav-item:hover {
  background: var(--color-navy-light);
  color: #fff;
  text-decoration: none;
}

.nav-item.active {
  background: rgba(21,101,192,0.25);
  color: #fff;
  border-left-color: var(--color-blue-light);
}

.nav-item__icon {
  font-size: 1rem;
  width: 1.25rem;
  text-align: center;
  flex-shrink: 0;
}

.sidebar__footer {
  padding: var(--space-4) var(--space-6);
  border-top: 1px solid var(--color-navy-light);
  font-size: var(--text-xs);
  color: rgba(255,255,255,0.35);
  line-height: 1.6;
}

/* ---- Mobile hamburger ---- */
.mobile-nav-toggle {
  display: none;
  position: fixed;
  top: var(--space-4);
  left: var(--space-4);
  z-index: calc(var(--z-nav) + 10);
  background: var(--color-navy);
  color: #fff;
  border-radius: var(--radius-md);
  padding: var(--space-2) var(--space-3);
  font-size: 1.25rem;
  line-height: 1;
  box-shadow: var(--shadow-md);
}

/* ---- Main content area ---- */
.main-content {
  margin-left: var(--nav-width);
  flex: 1;
  min-width: 0;
}

/* ---- Section container ---- */
.section {
  padding: var(--space-12) var(--space-8);
  max-width: var(--content-wide);
  margin: 0 auto;
}

.section--full {
  padding: 0;
  max-width: none;
}

.section-header {
  margin-bottom: var(--space-10);
}

.section-label {
  font-size: var(--text-sm);
  font-weight: var(--weight-semi);
  color: var(--color-teal);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: var(--space-2);
}

.section-title {
  font-size: var(--text-3xl);
  color: var(--text-primary);
  margin-bottom: var(--space-4);
}

.section-intro {
  font-size: var(--text-lg);
  color: var(--text-secondary);
  max-width: 65ch;
  line-height: var(--leading-loose);
}

/* ---- Alternating section bg ---- */
.page-section {
  border-bottom: var(--border-light);
}

.page-section:nth-child(even) { background: var(--bg-section-mid); }

/* ---- Grid utilities ---- */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-6);
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-6);
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-4);
}

.grid-auto {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-6);
}

/* ---- Responsive breakpoints ---- */
@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  :root { --nav-width: 0px; }

  .sidebar {
    transform: translateX(-260px);
    width: 260px;
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .mobile-nav-toggle { display: flex; align-items: center; }

  .main-content {
    margin-left: 0;
  }

  .section {
    padding: var(--space-10) var(--space-5);
  }

  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: 1fr;
  }

  .section-title { font-size: var(--text-2xl); }
}

@media (max-width: 480px) {
  .section { padding: var(--space-8) var(--space-4); }
  .grid-auto { grid-template-columns: 1fr; }
}

/* ---- Overlay for mobile nav ---- */
.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: calc(var(--z-nav) - 1);
}

.sidebar-overlay.active { display: block; }