body {
  font-family: system-ui, sans-serif;
  margin: 0;
  background: #0f172a;
  color: #e2e8f0;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 1.5rem;
  background: #1e293b;
}

main {
  display: grid;
  gap: 1rem;
  padding: 1rem;
}

#app-panel {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 1rem;
  min-height: 70vh;
}

aside, #chat-panel {
  background: #1e293b;
  border-radius: 8px;
  padding: 1rem;
}

#messages {
  min-height: 360px;
  max-height: 60vh;
  overflow-y: auto;
  margin-bottom: 1rem;
}

.msg {
  margin: 0.5rem 0;
  padding: 0.75rem;
  border-radius: 8px;
}

.msg.user { background: #334155; }
.msg.assistant { background: #0f766e; }

textarea, input {
  width: 100%;
  box-sizing: border-box;
  margin: 0.5rem 0;
  padding: 0.5rem;
  border-radius: 6px;
  border: 1px solid #475569;
  background: #0f172a;
  color: #e2e8f0;
}

button {
  padding: 0.5rem 1rem;
  border: none;
  border-radius: 6px;
  background: #2563eb;
  color: white;
  cursor: pointer;
}

.error { color: #f87171; }