body {
  font-family: Arial, sans-serif;
  background-color: #f2f2f2;
  margin: 0;
  padding: 0;
}

header {
  background-color: #333;
  color: #fff;
  text-align: center;
  padding: 10px;
}

#chat {
  max-width: 600px;
  margin: 0 auto;
  padding: 20px;
  background-color: #fff;
  border-radius: 5px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.2);
}

ul#messages {
  list-style: none;
  padding: 0;
  margin: 0;
  max-height: 300px;
  overflow-y: auto;
}

li.sent {
  background-color: #007bff;
  color: #fff;
  border-radius: 10px;
  padding: 5px;
  margin: 5px 0;
  float: right;
  clear: both;
}

li.receive {
  background-color: #f2f2f2;
  border-radius: 10px;
  padding: 5px;
  margin: 5px 0;
  float: left;
  clear: both;
}

form#message-form {
  display: flex;
  margin-top: 20px;
}

input#message-input {
  flex: 1;
  padding: 10px;
  border: 1px solid #ccc;
  border-radius: 5px;
}

button#message-btn {
  background-color: #007bff;
  color: #fff;
  border: none;
  border-radius: 5px;
  padding: 10px 20px;
  cursor: pointer;
}

button#message-btn:hover {
  background-color: #0056b3;
}