.mobile-topbar {
  display: none;
}

.mobile-overlay {
  display: none;
}

.app-shell {
  display: grid;
  grid-template-columns: var(--sidebar-w) var(--list-w) minmax(440px, 1fr) var(--details-w);
  height: 100vh;
  width: 100%;
  overflow: hidden;
  background: var(--background);
}

.sidebar,
.inbox-column,
.chat-column,
.details-column {
  min-width: 0;
  min-height: 0;
  background: var(--surface);
}

.sidebar {
  display: flex;
  flex-direction: column;
  gap: 18px;
  overflow-y: auto;
  padding: 16px 12px;
  border-right: 1px solid var(--border);
  background: var(--surface);
}

.inbox-column {
  display: flex;
  flex-direction: column;
  border-right: 1px solid var(--border);
  background: var(--background);
}

.chat-column {
  display: flex;
  flex-direction: column;
  background: var(--surface);
}

.details-column {
  display: block;
  overflow-y: auto;
  overflow-x: hidden;
  padding: 16px 16px 30px;
  border-left: 1px solid var(--border);
  background: var(--background);
}