body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 20px;
    background-color: #f5f5f5;
}

.chat-container {
    max-width: 800px;
    margin: 0 auto;
    background: white;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    padding: 20px;
}

h1 {
    text-align: center;
    color: #333;
}

.chat-messages {
    height: 600px;
    overflow-y: auto;
    border: 1px solid #ddd;
    border-radius: 4px;
    padding: 10px;
    margin-bottom: 10px;
    background: #fafafa;
}

.message {
    margin-bottom: 10px;
    padding: 8px;
    border-radius: 4px;
    background: #e9f5ff;
}

.user {
    font-weight: bold;
    color: #333;
}

.chat-input {
    display: flex;
    gap: 10px;
}

#message-input {
    flex-grow: 1;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 4px;
}

#send-button {
    padding: 10px 20px;
    background: #007bff;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
}

#send-button:hover {
    background: #0056b3;
}

.user-id-box {
    display: flex;
    justify-content: flex-end;
    margin-bottom: 10px;
}

#user-id-input {
    width: 120px;
    padding: 3px 7px;
    font-size: 0.92em;
    border-radius: 4px;
    border: 1px solid #ccc;
    background: #f8f9fa;
    text-align: right;
}

#save-user-id {
    padding: 4px 10px;
    font-size: 0.92em;
    border-radius: 4px;
    border: 1px solid #007bff;
    background: #007bff;
    color: #fff;
    cursor: pointer;
}