* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; height: 100vh; display: flex; flex-direction: column; background: #f4f4f4; }
.hidden { display: none !important; }

header { background: #232f3e; color: white; padding: 12px 20px; display: flex; justify-content: space-between; align-items: center; }
header h1 { font-size: 18px; font-weight: 600; }
#logout-btn { background: transparent; color: #ff9900; border: 1px solid #ff9900; padding: 6px 14px; border-radius: 4px; cursor: pointer; font-size: 13px; }

#login-screen { display: flex; justify-content: center; align-items: center; flex: 1; }
.login-box { background: white; padding: 32px; border-radius: 8px; box-shadow: 0 2px 8px rgba(0,0,0,0.1); width: 340px; }
.login-box h2 { margin-bottom: 20px; color: #232f3e; }
.login-box input { width: 100%; padding: 10px; margin-bottom: 12px; border: 1px solid #ccc; border-radius: 4px; font-size: 14px; }
.login-box button { width: 100%; padding: 10px; background: #0073bb; color: white; border: none; border-radius: 4px; cursor: pointer; font-size: 14px; }
.login-box button:hover { background: #005a94; }
#login-error { color: #d13212; font-size: 13px; margin-top: 8px; }

#chat-screen { display: flex; flex-direction: column; flex: 1; }
#messages { flex: 1; overflow-y: auto; padding: 16px; display: flex; flex-direction: column; gap: 10px; }
.message { max-width: 75%; padding: 10px 14px; border-radius: 12px; line-height: 1.5; font-size: 14px; word-wrap: break-word; }
.message.user { align-self: flex-end; background: #0073bb; color: white; border-bottom-right-radius: 4px; }
.message.assistant { align-self: flex-start; background: white; color: #232f3e; border: 1px solid #ddd; border-bottom-left-radius: 4px; }

#chat-form { display: flex; padding: 12px; background: white; border-top: 1px solid #ddd; gap: 8px; }
#user-input { flex: 1; padding: 10px; border: 1px solid #ccc; border-radius: 4px; font-size: 14px; }
#chat-form button { padding: 10px 20px; background: #0073bb; color: white; border: none; border-radius: 4px; cursor: pointer; font-size: 14px; }
#chat-form button:hover { background: #005a94; }