body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 20px;
    background-color: #f0f0f0;
}

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

h1, h2 {
    text-align: center;
    color: #333;
}

input[type="text"], input[type="password"], input[type="number"] {
    width: 100%;
    padding: 10px;
    margin: 10px 0;
    border: 1px solid #ddd;
    border-radius: 5px;
    box-sizing: border-box;
}

button {
    width: 100%;
    padding: 10px;
    background-color: #007bff;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    margin: 10px 0;
}

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

#chat-section {
    display: none;
}

#chat-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px;
    background-color: #007bff;
    color: white;
    border-radius: 5px;
}

#messages {
    height: 400px;
    overflow-y: auto;
    border: 1px solid #ddd;
    padding: 10px;
    margin: 10px 0;
    border-radius: 5px;
}

.message {
    margin: 10px 0;
    padding: 10px;
    border-radius: 5px;
    background-color: #f8f9fa;
}

.message.sent {
    background-color: #d1ecf1;
    text-align: right;
}

.message.received {
    background-color: #e2e3e5;
}

#message-input {
    display: flex;
    gap: 10px;
}

#message-text {
    flex: 1;
}

#receiver-id {
    width: 120px;
}

.user-item {
    padding: 5px;
    border-bottom: 1px solid #eee;
}

.user-item:hover {
    background-color: #f0f0f0;
    cursor: pointer;
}

#chat-with {
    padding: 10px;
    background-color: #e9ecef;
    border-radius: 5px;
    margin: 10px 0;
}