:root {
  color-scheme: dark;
  --bg: #212121;
  --sidebar: #171717;
  --border: #2f2f2f;
  --text: #ececec;
  --muted: #a5a5a5;
  --panel: #2a2a2a;
  --chip: #303030;
  --user: #2f6feb;
}

 {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: Inter, system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
}

.layout {
  min-height: 100vh;
  display: grid;
  grid-template-columns: 280px 1fr;
}

.sidebar {
  background: var(--sidebar);
  border-right: 1px solid var(--border);
  padding: 18px 14px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.brand {
  font-size: 1.7rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.ghost-btn,
.mode-select {
  width: 100%;
  border: 1px solid #3a3a3a;
  background: #242424;
  color: var(--text);
  border-radius: 10px;
  padding: 10px 12px;
  font: inherit;
}

.ghost-btn {
  text-align: left;
  cursor: pointer;
}

.nav-title {
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.chat-item {
  border-radius: 10px;
  padding: 10px 12px;
  color: #d4d4d4;
  background: transparent;
}

.chat-item.active,
.chat-item:hover {
  background: #2b2b2b;
}

.main-panel {
  display: grid;
  grid-template-rows: auto 1fr auto;
  min-width: 0;
}

.topbar {
  padding: 18px 24px;
  border-bottom: 1px solid var(--border);
}

.topbar h1 {
  margin: 0;
  font-size: 1.85rem;
  font-weight: 600;
}

.messages-wrap {
  overflow: hidden;
}

.messages {
  height: 100%;
  overflow-y: auto;
  padding: 24px 20px 120px;
}

.message {
  max-width: 780px;
  margin: 0 auto 14px;
  padding: 13px 15px;
  line-height: 1.5;
  border-radius: 14px;
  white-space: pre-wrap;
}

.message.bot {
  background: #2b2b2b;
}

.message.user {
  background: var(--user);
}

.composer {
  padding: 14px 20px 12px;
  background: linear-gradient(to top, rgba(33, 33, 33, 1), rgba(33, 33, 33, 0.92));
}

.composer-inner {
  max-width: 780px;
  margin: 0 auto;
  border: 1px solid #3e3e3e;
  border-radius: 28px;
  background: var(--panel);
  padding: 10px;
  display: flex;
  align-items: flex-end;
  gap: 10px;
}

#input {
  flex: 1;
  min-height: 24px;
  max-height: 180px;
  resize: none;
  border: 0;
  outline: none;
  background: transparent;
  color: var(--text);
  padding: 8px 10px;
  font: inherit;
}

#input::placeholder {
  color: #9a9a9a;
}

button[type="submit"] {
  border: 0;
  background: var(--chip);
  color: var(--text);
  border-radius: 999px;
  padding: 10px 16px;
  font: inherit;
  cursor: pointer;
}

button[type="submit"]:hover {
  background: #3b3b3b;
}

.disclaimer {
  max-width: 780px;
  margin: 8px auto 0;
  color: var(--muted);
  font-size: 0.85rem;
  text-align: center;
}

@media (max-width: 900px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .sidebar {
    display: none;
  }

  .topbar {
    padding: 14px 16px;
  }

  .messages {
    padding: 14px 12px 110px;
  }

  .composer {
    padding: 10px;
  }
}