body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  margin: 0;
  padding: 0;
  background: #e9ecef;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.chat-container {
  width: 100%;
  max-width: 600px;
  height: 90vh;
  background: #ffffff;
  border-radius: 10px;
  overflow: hidden;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
  display: flex;
  flex-direction: column;
}

.chat-header {
  background: #343a40;
  color: #ffffff;
  padding: 15px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.chat-header .user-name {
  font-size: 14px;
}

.logout-button {
  background: #dc3545;
  color: white;
  padding: 8px 14px;
  text-decoration: none;
  border-radius: 5px;
  font-size: 14px;
  transition: background 0.2s ease;
}

.logout-button:hover {
  background-color: #c82333;
}

.chat-messages {
  flex: 1;
  padding: 15px 20px;
  overflow-y: auto;
  background: #f1f3f5;
  font-size: 15px;
  flex-direction: column;
}

.chat-message {
  padding: 10px 15px;
  background: #ffffff;
  border-radius: 8px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.05);
  max-width: 80%;
  word-wrap: break-word;
}

.chat-message.system {
  background: transparent;
  box-shadow: none;
  color: #6c757d;
  font-style: italic;
}

.chat-form {
  display: flex;
  padding: 15px 20px;
  border-top: 1px solid #dee2e6;
  background: #ffffff;
}

.chat-form input {
  flex: 1;
  padding: 12px;
  border: 1px solid #ced4da;
  border-radius: 5px;
  font-size: 14px;
  margin-right: 10px;
}

.chat-form button {
  padding: 12px 20px;
  background: #007bff;
  color: white;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  font-size: 14px;
  transition: background 0.2s ease;
}

.chat-form button:hover {
  background: #0069d9;
}

.login-container {
  max-width: 400px;
  margin: 100px auto;
  padding: 30px;
  background: #fff;
  border-radius: 10px;
  box-shadow: 0 6px 20px rgba(0,0,0,0.1);
  text-align: center;
  font-family: 'Segoe UI', sans-serif;
}
.login-container h2 {
  margin-bottom: 20px;
  color: #333;
}
.login-container form {
  display: flex;
  flex-direction: column;
  gap: 15px;
}
.login-container input[type="text"] {
  padding: 12px;
  border: 1px solid #ced4da;
  border-radius: 5px;
  font-size: 14px;
}
.login-container button {
  padding: 12px;
  background-color: #007bff;
  color: white;
  border: none;
  border-radius: 5px;
  font-size: 14px;
  cursor: pointer;
}
.login-container button:hover {
  background-color: #0056b3;
}

.admin-container {
  max-width: 400px;
  margin: 80px auto;
  background: #ffffff;
  padding: 30px;
  border-radius: 10px;
  box-shadow: 0 6px 20px rgba(0,0,0,0.1);
  font-family: 'Segoe UI', sans-serif;
}
.admin-container h2 {
  text-align: center;
  margin-bottom: 20px;
}
.admin-container form {
  display: flex;
  flex-direction: column;
  gap: 15px;
}
.admin-container input[type="password"] {
  padding: 12px;
  border: 1px solid #ced4da;
  border-radius: 5px;
  font-size: 14px;
}
.admin-container button {
  padding: 12px;
  background-color: #007bff;
  color: white;
  border: none;
  border-radius: 5px;
  font-size: 14px;
  cursor: pointer;
}
.admin-container button:hover {
  background-color: #0056b3;
}
.admin-container .success {
  color: green;
  text-align: center;
}
.admin-container .error {
  color: red;
  text-align: center;
}