:root {
  --bg: #0b0f19;
  --panel: #111827;
  --panel-2: #0f172a;
  --line: #1f2937;
  --text: #e5e7eb;
  --muted: #9ca3af;
  --chip: #0b1220;
  --user: #1f2937;
  --assistant: #111827;
  --accent: #f9fafb;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: Inter, sans-serif;
  color: var(--text);
  background: var(--bg);
}

.shell {
  min-height: 100vh;
  display: grid;
  grid-template-columns: 260px 1fr;
}

.sidebar {
  border-right: 1px solid var(--line);
  background: #0a0f1c;
  padding: 12px;
}

.new-chat {
  width: 100%;
  border: 1px solid #263244;
  color: var(--text);
  background: #121a29;
  border-radius: 10px;
  padding: 10px;
  font-weight: 600;
  cursor: pointer;
}

.side-title {
  margin: 14px 2px 8px;
  color: var(--muted);
  font-size: 12px;
}

.history {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 6px;
}

.history li {
  border: 1px solid #1f2937;
  background: #0f1625;
  border-radius: 8px;
  padding: 10px;
  font-size: 13px;
  color: #cbd5e1;
}

.main {
  min-height: 100vh;
  display: grid;
  grid-template-rows: auto 1fr auto;
}

.topbar {
  height: 56px;
  border-bottom: 1px solid var(--line);
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 10px;
  padding: 0 16px;
  background: #0c1322;
}

.menu-btn {
  display: none;
  width: 32px;
  height: 32px;
  border-radius: 8px;
  border: 1px solid #243246;
  color: var(--text);
  background: #111827;
}

.top-title {
  font-weight: 600;
}

.top-model {
  font-size: 12px;
  color: var(--muted);
  border: 1px solid #273247;
  border-radius: 999px;
  padding: 5px 10px;
}

.chat {
  overflow-y: auto;
  padding: 22px 0;
}

.row {
  width: min(880px, 92%);
  margin: 0 auto 14px;
  display: grid;
  grid-template-columns: 28px 1fr;
  gap: 10px;
}

.avatar {
  width: 28px;
  height: 28px;
  border-radius: 7px;
  border: 1px solid #2a3448;
  display: grid;
  place-items: center;
  font-size: 12px;
  color: #d1d5db;
  background: #101827;
}

.bubble {
  border: 1px solid #253247;
  border-radius: 10px;
  padding: 10px 12px;
  line-height: 1.5;
  white-space: pre-wrap;
}

.row.user .bubble { background: var(--user); }
.row.bot .bubble { background: var(--assistant); }
.row.typing .bubble { color: var(--muted); font-style: italic; }

.empty {
  width: min(880px, 92%);
  margin: 12vh auto 0;
  text-align: center;
  color: var(--muted);
}

.empty h2 {
  margin: 0 0 8px;
  color: var(--text);
  font-size: 26px;
}

.composer {
  border-top: 1px solid var(--line);
  background: #0c1322;
  padding: 12px;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 8px;
}

.composer input {
  border: 1px solid #273247;
  border-radius: 10px;
  background: var(--panel-2);
  color: var(--text);
  padding: 12px;
  font-size: 14px;
  outline: none;
}

.composer button {
  border: 1px solid #2f3b52;
  border-radius: 10px;
  background: #f3f4f6;
  color: #0b1220;
  padding: 0 14px;
  font-weight: 600;
  cursor: pointer;
}

.composer button:disabled { opacity: .6; cursor: not-allowed; }

@media (max-width: 900px) {
  .shell { grid-template-columns: 1fr; }
  .sidebar {
    position: fixed;
    left: -280px;
    top: 0;
    bottom: 0;
    width: 260px;
    z-index: 20;
    transition: left .2s ease;
  }
  .sidebar.open { left: 0; }
  .menu-btn { display: inline-grid; place-items: center; }
}