:root {
  /* Light theme (default) */
  --bg: #f7f7f5;
  --panel: #ffffff;
  --text: #111111;
  --muted: #555555;
  --border: rgba(0, 0, 0, 0.10);
  --danger: #b00020;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #101010;
    --panel: #151515;
    --text: #f2f2f2;
    --muted: #b7b7b7;
    --border: rgba(255, 255, 255, 0.10);
    --danger: #ff5a6a;
    --shadow: 0 18px 60px rgba(0, 0, 0, 0.50);
  }
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
  margin: 0;
  color: var(--text);
  background: var(--bg);
  font: 14px/1.35 system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, sans-serif;
}

code { font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace; }

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 16px;
  border-bottom: 1px solid var(--border);
  background: var(--panel);
  position: sticky;
  top: 0;
  z-index: 10;
}

.brand {
  display: flex;
  gap: 10px;
  align-items: center;
}
.brand-title { font-weight: 760; letter-spacing: 0.2px; }
.brand-subtitle { color: var(--muted); font-size: 12px; margin-top: 1px; }

.topbar-actions { display: flex; gap: 10px; }

.layout {
  display: grid;
  grid-template-columns: 340px 1fr;
  height: calc(100vh - 58px);
}

.sidebar {
  border-right: 1px solid var(--border);
  background: var(--panel);
  padding: 12px;
  overflow: hidden;
}
.sidebar-header {
  display: flex;
  gap: 10px;
  margin-bottom: 10px;
}
.chats {
  overflow: auto;
  height: calc(100% - 44px);
  padding-right: 4px;
}

.chat {
  display: grid;
  grid-template-rows: auto 1fr auto;
  height: 100%;
  overflow: hidden;
}

.status {
  margin: 12px;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 12px;
  color: var(--muted);
  background: var(--panel);
}
.hidden { display: none; }

.messages {
  overflow: auto;
  padding: 18px 18px 6px 18px;
}

.composer {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 10px;
  padding: 14px 16px;
  border-top: 1px solid var(--border);
  background: var(--panel);
}

.prompt {
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  padding: 12px 12px;
  border-radius: 12px;
  outline: none;
}
.prompt:focus { border-color: rgba(0, 0, 0, 0.22); }

.btn {
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  font-weight: 720;
  padding: 10px 12px;
  border-radius: 12px;
  cursor: pointer;
}
.btn.secondary {
  background: var(--panel);
  color: var(--text);
}
.btn.danger {
  background: var(--panel);
  color: var(--danger);
  border-color: var(--danger);
}
.btn:hover { box-shadow: var(--shadow); }
.btn:active { transform: translateY(1px); }
.btn:disabled { opacity: 0.55; cursor: not-allowed; }

.chat-item {
  display: grid;
  gap: 6px;
  padding: 10px 10px;
  border-radius: 12px;
  border: 1px solid transparent;
  cursor: pointer;
}
.chat-item:hover { background: rgba(0, 0, 0, 0.04); }
.chat-item.active { background: rgba(0, 0, 0, 0.06); border-color: rgba(0, 0, 0, 0.12); }
.chat-title { font-weight: 700; }
.chat-meta { color: var(--muted); font-size: 12px; display: flex; gap: 8px; }

.msg {
  max-width: 860px;
  margin: 0 auto 12px auto;
  padding: 12px 12px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--panel);
  white-space: pre-wrap;
}
.msg.user {
  background: var(--panel);
}
.msg.assistant {
  background: var(--panel);
}
.msg-role { color: var(--muted); font-size: 12px; margin-bottom: 6px; }

.dialog::backdrop {
  background: rgba(0, 0, 0, 0.6);
}
.dialog {
  border: 1px solid var(--border);
  border-radius: 18px;
  width: min(640px, calc(100vw - 28px));
  background: var(--panel);
  color: var(--text);
  box-shadow: var(--shadow);
}
.dialog-inner { padding: 16px; }
.dialog-title { font-size: 16px; font-weight: 760; margin-bottom: 12px; }
.label { display: grid; gap: 6px; margin: 12px 0; }
.label-title { font-weight: 680; }
.input {
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  padding: 10px 10px;
  border-radius: 12px;
  outline: none;
}
.hint { color: var(--muted); font-size: 12px; }
.dialog-actions { display: flex; justify-content: flex-end; gap: 10px; margin-top: 14px; }

@media (max-width: 900px) {
  .layout { grid-template-columns: 1fr; }
  .sidebar { height: 240px; border-right: none; border-bottom: 1px solid var(--border); }
}