:root {
  color-scheme: light;
  font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --bg: #f5f7fb;
  --card: #ffffff;
  --text: #18212f;
  --muted: #5c6878;
  --border: #dde4ef;
  --accent: #2251d1;
  --accent-soft: #edf2ff;
  --assistant: #f3f6fb;
  --user: #2251d1;
  --user-text: #ffffff;
  --danger: #c53b3b;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
}

.app-shell {
  min-height: 100vh;
  display: grid;
  grid-template-rows: auto 1fr auto;
  max-width: 920px;
  margin: 0 auto;
  padding: 12px;
  gap: 12px;
}

.topbar,
.chat-panel,
.composer {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: 0 4px 20px rgba(21, 33, 58, 0.05);
}

.topbar {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 12px;
  padding: 14px 16px;
}

.topbar h1 {
  margin: 2px 0 0;
  font-size: 1rem;
  line-height: 1.3;
}

.eyebrow {
  font-size: 0.75rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.session-meta {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.badge {
  display: inline-flex;
  align-items: center;
  min-height: 32px;
  padding: 0 10px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 600;
}

.ghost-button,
.composer button {
  border: 0;
  border-radius: 12px;
  cursor: pointer;
  font: inherit;
}

.ghost-button {
  height: 32px;
  padding: 0 12px;
  background: transparent;
  color: var(--muted);
}

.ghost-button:hover {
  background: #f1f4f9;
}

.chat-panel {
  min-height: 0;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.status-banner {
  min-height: 42px;
  padding: 12px 16px 0;
  color: var(--muted);
  font-size: 0.88rem;
}

.status-banner.error {
  color: var(--danger);
}

.messages {
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 8px 12px 14px;
  overflow-y: auto;
}

.message {
  display: grid;
  gap: 6px;
  max-width: min(100%, 760px);
  padding: 12px 14px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--assistant);
}

.message.user {
  margin-left: auto;
  background: var(--user);
  color: var(--user-text);
  border-color: transparent;
}

.message-role {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  opacity: 0.78;
}

.message-body {
  white-space: pre-wrap;
  line-height: 1.45;
  font-size: 0.95rem;
}

.message-sources {
  display: grid;
  gap: 6px;
}

.source-card {
  padding: 8px 10px;
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.78);
  color: var(--text);
  font-size: 0.82rem;
}

.message.user .source-card {
  background: rgba(255, 255, 255, 0.14);
  color: var(--user-text);
}

.source-title {
  font-weight: 600;
  margin-bottom: 4px;
}

.source-meta {
  color: var(--muted);
}

.message.user .source-meta {
  color: rgba(255, 255, 255, 0.82);
}

.composer {
  position: sticky;
  bottom: 0;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 10px;
  padding: 10px;
}

.composer textarea {
  width: 100%;
  min-height: 52px;
  max-height: 180px;
  resize: none;
  padding: 14px 16px;
  border: 1px solid var(--border);
  border-radius: 12px;
  font: inherit;
  line-height: 1.4;
  color: var(--text);
  background: #fbfcfe;
}

.composer textarea:focus {
  outline: 2px solid rgba(34, 81, 209, 0.15);
  border-color: var(--accent);
}

.composer button {
  min-width: 112px;
  padding: 0 16px;
  background: var(--accent);
  color: #fff;
  font-weight: 600;
}

.composer button:disabled,
.ghost-button:disabled {
  opacity: 0.6;
  cursor: wait;
}

@media (max-width: 720px) {
  .app-shell {
    padding: 8px;
    gap: 8px;
  }

  .topbar {
    flex-direction: column;
    align-items: stretch;
  }

  .session-meta {
    justify-content: space-between;
  }

  .composer {
    grid-template-columns: 1fr;
  }

  .composer button {
    height: 48px;
  }
}