.app-shell {
  min-height: 100vh;
  display: grid;
  grid-template-columns: 292px 1fr;
}

.sidebar {
  background: #ffffff;
  border-right: 1px solid var(--line);
  padding: 22px 16px;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 4px 6px 24px;
  border-bottom: 1px solid var(--line);
  margin-bottom: 18px;
}

.brand-mark {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  display: grid;
  place-items: center;
  background: var(--primary);
  color: #fff;
  font-weight: 800;
  letter-spacing: .03em;
}

.brand-title { font-size: 15px; font-weight: 800; }
.brand-subtitle { color: var(--muted); font-size: 12px; margin-top: 2px; }

.sidebar-nav { display: grid; gap: 10px; }
.nav-group { border-radius: 14px; }
.nav-group-title {
  width: 100%;
  border: 0;
  background: transparent;
  color: var(--muted);
  padding: 10px 10px;
  text-align: left;
  font-weight: 800;
  font-size: 12px;
  letter-spacing: .05em;
  text-transform: uppercase;
  display: flex;
  justify-content: space-between;
  cursor: pointer;
}
.nav-group-items { display: none; padding: 2px; }
.nav-group.is-open .nav-group-items { display: grid; gap: 4px; }
.nav-group.is-open .nav-group-title span { transform: rotate(180deg); }

.nav-item {
  padding: 11px 12px;
  border-radius: 12px;
  color: #3d4a5b;
  font-weight: 650;
  display: block;
  border: 1px solid transparent;
}
.nav-item:hover { background: #f2f5f8; }
.nav-item.active {
  background: #eef4f8;
  border-color: #d5e2ea;
  color: var(--primary);
}

.main { min-width: 0; }
.topbar {
  height: 86px;
  background: rgba(255,255,255,.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 0 28px;
  position: sticky;
  top: 0;
  z-index: 10;
}
.topbar h1 { margin: 0; font-size: 22px; letter-spacing: -.02em; }
.topbar p { margin: 4px 0 0; color: var(--muted); font-size: 13px; }
.topbar-actions { margin-left: auto; display: flex; gap: 10px; }
.content { padding: 28px; max-width: 1460px; }

@media (max-width: 900px) {
  .app-shell { grid-template-columns: 1fr; }
  .sidebar { position: fixed; left: -310px; width: 292px; z-index: 20; transition: left .2s ease; }
  body.sidebar-open .sidebar { left: 0; }
  .topbar-actions { display: none; }
  .content { padding: 18px; }
}