/* ============================================================
   Blank Space — Layout shell (Session 2C)
   Desktop-first per blueprint 7.5. One breakpoint: 900px.
   ============================================================ */

.bs-shell {
  display: flex;
  min-height: 100vh;
}

/* --- Sidebar (desktop, >= 900px) --- */
.bs-sidebar {
  width: var(--sidebar-width);
  flex-shrink: 0;
  background: var(--bg-surface);
  border-right: 1px solid var(--border);
  padding: var(--space-6) var(--space-4);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
}
.bs-wordmark {
  font-family: var(--font-display);
  font-size: var(--text-lg-size);
  line-height: var(--text-lg-lh);
  margin-bottom: var(--space-6);
}
.bs-sidebar-nav {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  flex: 1;
}
.bs-nav-item {
  font-size: var(--text-sm-size);
  color: var(--text-secondary);
  text-decoration: none;
  padding: var(--space-2) 0;
}
.bs-nav-item--active { color: var(--accent); }
.bs-heartbeat-slot { margin-top: auto; }

/* --- Content area --- */
.bs-content {
  flex: 1;
  margin-left: var(--sidebar-width);
  max-width: var(--content-max-width);
  padding: var(--space-8);
}

/* --- Tab bar (mobile, < 900px) --- */
.bs-tabbar {
  display: none;
}

@media (max-width: 899px) {
  .bs-sidebar { display: none; }
  .bs-content {
    margin-left: 0;
    max-width: 100%;
    padding: var(--space-4);
    padding-bottom: 72px; /* clears the fixed tab bar */
  }
  .bs-tabbar {
    display: flex;
    justify-content: space-around;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--bg-surface);
    border-top: 1px solid var(--border);
    padding: var(--space-2) 0;
  }
  .bs-tab-item {
    font-size: var(--text-xs-size);
    color: var(--text-secondary);
    text-decoration: none;
    text-align: center;
    flex: 1;
  }
  .bs-tab-item--active { color: var(--accent); }
}

/* --- Two-column module layout (Home 5.1, reused later by Action Center) --- */
.bs-two-col {
  display: flex;
  gap: var(--space-6);
}
.bs-col {
  flex: 1;
  min-width: 0;
}
@media (max-width: 899px) {
  .bs-two-col { flex-direction: column; }
}

/* --- Detail views stay single-column at a comfortable reading width --- */
.bs-detail {
  max-width: var(--detail-reading-width);
}

.bs-stub-note {
  color: var(--text-muted);
  font-size: var(--text-sm-size);
}