:root {
  --bg: #f5f6f8;
  --panel-bg: #ffffff;
  --border: #d9dde3;
  --text: #1c2128;
  --muted: #6b7280;
  --accent: #2563eb;
  --user-bubble: #2563eb;
  --user-text: #ffffff;
  --assistant-bubble: #eef1f5;
  --assistant-text: #1c2128;
  --ok: #15803d;
  --fail: #b91c1c;
  --info: #6b7280;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
  height: 100vh;
  display: flex;
  flex-direction: column;
}

#app-header {
  padding: 12px 20px;
  background: var(--panel-bg);
  border-bottom: 1px solid var(--border);
}
#app-header h1 { margin: 0; font-size: 1.2rem; }
#app-header .year { color: var(--accent); }
.disclaimer { margin: 4px 0 0; font-size: 0.8rem; color: var(--muted); }

#split {
  flex: 1;
  display: flex;
  min-height: 0;
}

.panel {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;
  padding: 16px;
  overflow: hidden;
}
#chat-panel { border-right: 1px solid var(--border); }

.panel-title { margin: 0 0 8px; font-size: 1rem; }
.trail-note { margin: 0 0 8px; font-size: 0.75rem; color: var(--muted); }

/* Chat messages */
.messages {
  flex: 1;
  overflow-y: auto;
  padding: 8px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.msg {
  max-width: 80%;
  padding: 8px 12px;
  border-radius: 12px;
  font-size: 0.9rem;
  line-height: 1.4;
  white-space: pre-wrap;
  word-wrap: break-word;
}
.msg.user {
  align-self: flex-end;
  background: var(--user-bubble);
  color: var(--user-text);
  border-bottom-right-radius: 2px;
}
.msg.assistant {
  align-self: flex-start;
  background: var(--assistant-bubble);
  color: var(--assistant-text);
  border-bottom-left-radius: 2px;
}
.msg.system {
  align-self: center;
  background: transparent;
  color: var(--muted);
  font-size: 0.8rem;
  font-style: italic;
}

/* Composer */
.composer {
  display: flex;
  gap: 8px;
  margin-top: 10px;
}
#message-input {
  flex: 1;
  padding: 9px 12px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 0.9rem;
}
#send-btn {
  padding: 9px 18px;
  border: none;
  border-radius: 6px;
  background: var(--accent);
  color: #fff;
  font-size: 0.9rem;
  cursor: pointer;
}
#send-btn:disabled { opacity: 0.5; cursor: default; }

/* Actions row */
.actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-top: 10px;
  font-size: 0.85rem;
}
/* Clickable action buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 9px 16px;
  border-radius: 6px;
  font-size: 0.85rem;
  font-weight: 600;
  line-height: 1;
  cursor: pointer;
  text-decoration: none;
  border: 1px solid transparent;
  transition: filter 0.15s ease, box-shadow 0.15s ease;
}
.btn:hover { filter: brightness(0.96); }
.btn:active { filter: brightness(0.9); }
.btn-primary { background: var(--accent); color: #fff; border-color: var(--accent); }
.btn-secondary { background: #fff; color: var(--accent); border-color: var(--accent); }
.btn-success {
  background: var(--ok);
  color: #fff;
  border-color: var(--ok);
  box-shadow: 0 0 0 3px rgba(21, 128, 61, 0.15);
}
.btn.disabled,
.btn[aria-disabled="true"] {
  background: var(--assistant-bubble);
  color: var(--muted);
  border-color: var(--border);
  box-shadow: none;
  cursor: default;
  pointer-events: none;
  filter: none;
}
.file-label input { display: none; }

/* Observation trail */
.trail {
  flex: 1;
  overflow-y: auto;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--panel-bg);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.78rem;
}
.trail-row {
  padding: 6px 10px;
  border-bottom: 1px solid var(--border);
  display: grid;
  grid-template-columns: auto auto auto auto;
  gap: 8px;
  align-items: baseline;
}
.trail-row .summary {
  grid-column: 1 / -1;
  color: var(--text);
}
.trail-row .ts { color: var(--muted); }
.trail-row .event { font-weight: 600; }
.trail-row .node { color: var(--muted); }
.trail-row .status { font-weight: 600; text-transform: uppercase; }
.trail-row .status.ok { color: var(--ok); }
.trail-row .status.fail { color: var(--fail); }
.trail-row .status.info { color: var(--info); }
.trail-empty { padding: 12px; color: var(--muted); font-style: italic; }