/* ============================================================
   App shell — Sidebar + Header + layout grid (brief §4-5, §31)
   ============================================================ */
.app-shell { display: flex; min-height: 100vh; }

/* --- Sidebar --- */
.sidebar {
  width: var(--sidebar-width); flex: none; background: var(--color-primary);
  display: flex; flex-direction: column; position: sticky; top: 0; height: 100vh;
  transition: width var(--transition-base); z-index: 20;
}
.sidebar-collapsed { width: var(--sidebar-width-collapsed); }

.sidebar-brand { display: flex; align-items: center; gap: 10px; padding: 18px 16px; flex: none; min-height: var(--header-height); }
.sidebar-brand-mark {
  width: 32px; height: 32px; border-radius: var(--radius-md); background: rgba(255,255,255,.12);
  color: #fff; display: flex; align-items: center; justify-content: center; font-weight: 700; flex: none;
}
.sidebar-brand-name { color: #fff; font: var(--text-card-title); line-height: 1.2; }
.sidebar-brand-sub { color: rgba(255,255,255,.5); font-size: 11px; margin-top: 1px; }

.sidebar-nav { flex: 1; overflow-y: auto; padding: var(--space-2) var(--space-3) var(--space-4); }
.nav-item, .nav-group-toggle {
  display: flex; align-items: center; gap: 11px; width: 100%; padding: 9px 10px; margin-bottom: 1px;
  border-radius: var(--radius-md); color: rgba(255,255,255,.68); background: none; border: none; cursor: pointer;
  font: var(--text-body-medium); font-size: 13.5px; text-align: left; transition: background var(--transition-fast), color var(--transition-fast);
}
.nav-item:hover, .nav-group-toggle:hover { background: rgba(255,255,255,.06); color: #fff; }
.nav-item.active { background: rgba(255,255,255,.12); color: #fff; }
.nav-group-toggle.active { color: #fff; }
.nav-group-chevron { margin-left: auto; transition: transform var(--transition-fast); }
.nav-group-chevron.open { transform: rotate(180deg); }
.nav-subitems { padding-left: 41px; display: flex; flex-direction: column; }
.nav-subitem {
  padding: 7px 10px; color: rgba(255,255,255,.55); font-size: 13px; border-radius: var(--radius-sm);
  border-left: 1.5px solid rgba(255,255,255,.12); margin-left: 2px; transition: color var(--transition-fast), border-color var(--transition-fast);
}
.nav-subitem:hover { color: #fff; }
.nav-subitem.active { color: #fff; border-left-color: var(--color-secondary); font-weight: 600; }
.sidebar-collapsed .nav-item, .sidebar-collapsed .nav-group-toggle { justify-content: center; }

.sidebar-collapse-btn {
  flex: none; margin: var(--space-2); align-self: flex-end; width: 28px; height: 28px; border-radius: 50%;
  background: rgba(255,255,255,.08); color: rgba(255,255,255,.7); border: none; cursor: pointer;
  display: flex; align-items: center; justify-content: center; transition: background var(--transition-fast);
}
.sidebar-collapse-btn:hover { background: rgba(255,255,255,.16); color: #fff; }

/* --- Header --- */
.app-header {
  height: var(--header-height); flex: none; background: var(--color-surface); border-bottom: 1px solid var(--color-border);
  display: flex; align-items: center; gap: var(--space-4); padding: 0 var(--space-6); position: sticky; top: 0; z-index: 10;
}
.header-menu-btn { display: none; background: none; border: none; color: var(--color-text-secondary); cursor: pointer; padding: 6px; }
.header-search {
  display: flex; align-items: center; gap: 8px; background: var(--color-surface-alt); border: 1px solid var(--color-border);
  border-radius: var(--radius-md); padding: 7px 12px; width: 320px; color: var(--color-text-muted);
  transition: border-color var(--transition-fast), background var(--transition-fast);
}
.header-search:focus-within { border-color: var(--color-secondary); background: var(--color-surface); }
.header-search input { border: none; background: none; outline: none; font: var(--text-body); width: 100%; color: var(--color-text); }
.header-actions { margin-left: auto; display: flex; align-items: center; gap: var(--space-2); }
.header-icon-btn {
  position: relative; width: 36px; height: 36px; border-radius: 50%; display: flex; align-items: center; justify-content: center;
  color: var(--color-text-secondary); background: none; border: none; cursor: pointer; transition: background var(--transition-fast);
}
.header-icon-btn:hover { background: var(--color-surface-alt); color: var(--color-text); }
.header-icon-dot { position: absolute; top: 7px; right: 8px; width: 7px; height: 7px; border-radius: 50%; background: var(--color-danger); border: 1.5px solid var(--color-surface); }

.header-user { position: relative; display: flex; align-items: center; gap: 9px; padding: 5px 8px 5px 5px; border-radius: var(--radius-md); cursor: pointer; transition: background var(--transition-fast); }
.header-user:hover { background: var(--color-surface-alt); }
.header-user-name { font: var(--text-body-medium); font-size: 13.5px; line-height: 1.25; }
.header-user-role { font: var(--text-caption); font-size: 11.5px; color: var(--color-text-muted); }
.header-user-menu {
  position: absolute; top: calc(100% + 6px); right: 0; background: var(--color-surface); border: 1px solid var(--color-border);
  border-radius: var(--radius-md); box-shadow: var(--shadow-md); min-width: 160px; padding: 6px; z-index: 30;
}
.header-user-menu button {
  display: flex; align-items: center; gap: 8px; width: 100%; padding: 8px 10px; background: none; border: none;
  border-radius: var(--radius-sm); text-align: left; font: var(--text-body); cursor: pointer; color: var(--color-text);
}
.header-user-menu button:hover { background: var(--color-surface-alt); }

/* --- Main content area --- */
.app-main { flex: 1; min-width: 0; display: flex; flex-direction: column; }
.page-content { padding: var(--space-6); max-width: 1440px; width: 100%; margin: 0 auto; }

.sidebar-mobile-overlay { display: none; }

.app-boot { min-height: 100vh; display: flex; align-items: center; justify-content: center; background: var(--color-bg); }
.app-boot-mark {
  width: 44px; height: 44px; border-radius: var(--radius-lg); background: var(--color-primary); color: #fff;
  display: flex; align-items: center; justify-content: center; font-weight: 700; font-size: 18px;
  animation: boot-pulse 1.1s ease-in-out infinite;
}
@keyframes boot-pulse { 0%, 100% { opacity: 1; } 50% { opacity: 0.45; } }

@media (max-width: 900px) {
  .sidebar-mobile-overlay { display: block; position: fixed; inset: 0; background: rgba(15,37,64,.4); z-index: 15; }
  .header-search { display: none; }
  .header-menu-btn { display: flex; }
  .sidebar { position: fixed; left: -100%; top: 0; height: 100vh; transition: left var(--transition-base); }
  .sidebar.sidebar-mobile-open { left: 0; box-shadow: var(--shadow-lg); }
  .sidebar-collapse-btn { display: none; }
  .page-content { padding: var(--space-4); }
}