:root {
  --bg: #212121;
  --sidebar: #171717;
  --panel: #2f2f2f;
  --text: #ececec;
  --muted: #afafaf;
  --border: #3a3a3a;
  --user: #2f2f2f;
  --accent: #fff;
  --danger: #ff6b6b;
  --radius: 24px;
  --font: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; }
body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
}

.hidden { display: none !important; }

/* Login — same full-screen gate as ChatGPT-style apps */
.login-gate {
  min-height: 100%;
  display: grid;
  place-items: center;
  padding: 24px;
  background: var(--bg);
}
.login-card {
  width: min(360px, 100%);
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.login-brand {
  font-size: 28px;
  font-weight: 600;
  letter-spacing: -0.02em;
}
.login-sub { margin: 0 0 8px; color: var(--muted); font-size: 14px; }
.login-card input {
  width: 100%;
  padding: 12px 14px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  font: inherit;
  font-size: 15px;
}
.login-card button {
  padding: 11px 14px;
  border: 0;
  border-radius: 10px;
  background: var(--accent);
  color: #111;
  font: inherit;
  font-weight: 600;
  cursor: pointer;
}
.login-card .error { color: var(--danger); font-size: 13px; margin: 0; }

.app {
  display: grid;
  grid-template-columns: 260px 1fr;
  height: 100%;
}

.sidebar {
  background: var(--sidebar);
  display: flex;
  flex-direction: column;
  padding: 12px;
  gap: 10px;
  border-right: 1px solid #000;
}
.new-chat {
  width: 100%;
  text-align: left;
  padding: 10px 12px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text);
  font: inherit;
  cursor: pointer;
}
.new-chat:hover { background: #212121; }
.chat-list {
  flex: 1;
  overflow: auto;
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.chat-item {
  text-align: left;
  padding: 10px 12px;
  border: 0;
  border-radius: 10px;
  background: transparent;
  color: var(--text);
  font: inherit;
  font-size: 14px;
  cursor: pointer;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.chat-item.active, .chat-item:hover { background: #212121; }
.sidebar-foot {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding-top: 8px;
  border-top: 1px solid #2a2a2a;
}
.model-pill {
  font-size: 12px;
  color: var(--muted);
  padding: 4px 2px;
}
.linkish {
  background: none;
  border: 0;
  color: var(--muted);
  text-align: left;
  padding: 4px 2px;
  font: inherit;
  font-size: 13px;
  cursor: pointer;
}
.linkish:hover { color: var(--text); }

.main {
  display: grid;
  grid-template-rows: auto 1fr auto;
  min-width: 0;
  height: 100%;
  position: relative;
}
.topbar {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 16px;
  border-bottom: 1px solid #2a2a2a;
}
.topbar-title { font-weight: 600; font-size: 14px; flex: 1; min-width: 0; }
.lock-chip {
  margin-left: auto;
  padding: 6px 12px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text);
  font: inherit;
  font-size: 13px;
  cursor: pointer;
}
.lock-chip:hover { background: var(--panel); }
.lock-btn {
  width: 100%;
  text-align: left;
  padding: 10px 12px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: #2a2a2a;
  color: var(--text);
  font: inherit;
  font-size: 14px;
  cursor: pointer;
}
.lock-btn:hover { background: #333; }
.ghost {
  display: none;
  background: none;
  border: 0;
  color: var(--text);
  font-size: 18px;
  cursor: pointer;
}

.empty {
  position: absolute;
  inset: 56px 0 120px;
  display: grid;
  place-content: center;
  text-align: center;
  pointer-events: none;
}
.empty h1 { margin: 0 0 8px; font-size: 32px; font-weight: 600; letter-spacing: -0.03em; }
.empty p { margin: 0; color: var(--muted); }

.messages {
  overflow: auto;
  padding: 24px 16px 12px;
  display: flex;
  flex-direction: column;
  gap: 18px;
}
.msg {
  width: min(720px, 100%);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 36px 1fr;
  gap: 14px;
  align-items: start;
}
.avatar {
  width: 32px;
  height: 32px;
  border-radius: 999px;
  display: grid;
  place-items: center;
  font-size: 12px;
  font-weight: 700;
  flex-shrink: 0;
}
.avatar.user { background: #5436da; color: #fff; }
.avatar.assistant { background: #10a37f; color: #fff; }
.bubble {
  padding: 2px 0;
  font-size: 15.5px;
  line-height: 1.65;
  white-space: pre-wrap;
  word-break: break-word;
}
.msg.user .bubble {
  background: var(--user);
  border-radius: 18px;
  padding: 10px 14px;
}
.msg.pending .bubble { color: var(--muted); }

.composer-wrap {
  padding: 8px 16px 16px;
  background: linear-gradient(to top, var(--bg) 70%, transparent);
}
.composer {
  width: min(720px, 100%);
  margin: 0 auto;
  display: flex;
  align-items: flex-end;
  gap: 8px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 10px 10px 10px 16px;
}
.composer textarea {
  flex: 1;
  resize: none;
  border: 0;
  outline: none;
  background: transparent;
  color: var(--text);
  font: inherit;
  font-size: 15.5px;
  line-height: 1.45;
  max-height: 200px;
  padding: 6px 0;
}
.composer button {
  width: 36px;
  height: 36px;
  border: 0;
  border-radius: 999px;
  background: var(--accent);
  color: #111;
  font-size: 18px;
  font-weight: 700;
  cursor: pointer;
  flex-shrink: 0;
}
.composer button:disabled {
  opacity: 0.35;
  cursor: default;
}
.disclaimer {
  width: min(720px, 100%);
  margin: 8px auto 0;
  text-align: center;
  color: var(--muted);
  font-size: 12px;
}

@media (max-width: 800px) {
  .app { grid-template-columns: 1fr; }
  .sidebar {
    position: fixed;
    inset: 0 auto 0 0;
    width: min(280px, 86vw);
    z-index: 20;
    transform: translateX(-105%);
    transition: transform 0.2s ease;
  }
  .sidebar.open { transform: translateX(0); }
  .ghost { display: inline-block; }
}