.app-shell {
  display: grid;
  grid-template-columns: 360px 1fr 1fr;
  grid-template-rows: auto auto auto 1fr;
  grid-template-areas:
    "header header header"
    "check  check  check"
    "config tuples graph"
    "model  tuples graph";
  height: 100vh;
  gap: 1px;
  background: var(--border-color);
}

.app-header {
  grid-area: header;
  background: var(--bg);
  padding: 16px 24px;
  display: flex;
  align-items: baseline;
  gap: 16px;
}

.app-header h1 {
  font-family: var(--font-display);
  font-size: 22px;
  font-weight: 400;
  color: var(--fg);
  letter-spacing: 0.01em;
}

.header-sub {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 400;
  color: var(--fg-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.header-source {
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 500;
  color: var(--accent-teal);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 3px 8px;
  border: 1px solid var(--accent-teal);
  border-radius: 3px;
  opacity: 0.8;
}

.color-mode-control {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 8px;
}

.control-label {
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 500;
  color: var(--fg-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

.panel {
  display: flex;
  flex-direction: column;
  overflow: hidden;
  background: var(--bg-elevated);
}

#check-panel  { grid-area: check; }
#config-panel { grid-area: config; }
#model-panel  { grid-area: model; }
#tuples-panel { grid-area: tuples; }
#graph-panel  { grid-area: graph; }

/* When config panel is collapsed, model spans both rows */
#model-panel.expanded {
  grid-row: 3 / 5;
}

/* When collapsed, only the header row remains visible */

.panel-header {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-shrink: 0;
}

.panel-label {
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 500;
  color: var(--fg-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

.panel-count {
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--fg-dim);
}

.panel-body {
  flex: 1;
  overflow-y: auto;
  padding: 12px 16px;
}

.panel-body-graph {
  padding: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* Collapsible panel toggle */
.panel-toggle {
  background: none;
  border: none;
  color: var(--fg-muted);
  cursor: pointer;
  font-size: 12px;
  padding: 2px 6px;
  transition: transform 0.2s;
}

.panel-toggle:hover {
  color: var(--fg);
}

.panel.collapsed .panel-toggle {
  transform: rotate(-90deg);
}

.panel.collapsed .panel-body {
  display: none;
}

@media (max-width: 900px) {
  .app-shell {
    grid-template-columns: 1fr;
    grid-template-rows: auto auto auto auto auto 300px;
    grid-template-areas:
      "header"
      "check"
      "config"
      "model"
      "tuples"
      "graph";
    height: auto;
    min-height: 100vh;
  }

  #model-panel.expanded {
    grid-row: auto;
  }

  #model-panel,
  #tuples-panel {
    max-height: 50vh;
  }
}