body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    height: 100vh;
    background-color: #f0f0f0;
}

#username-prompt, #room-selection, #chat-container {
    padding: 20px;
    margin: auto;
    width: 100%;
    max-width: 500px;
    box-sizing: border-box;
}

#chat-window {
    height: 400px;
    border: 1px solid #ccc;
    background: #fff;
    overflow-y: scroll;
    padding: 10px;
    margin-bottom: 10px;
}

.message {
    margin-bottom: 10px;
    padding: 5px;
    border-radius: 5px;
}

.sent {
    background-color: #d9edf7;
    text-align: right;
    margin-left: auto;
    margin-right: 0;
}

.received {
    background-color: #f5f5f5;
    text-align: left;
    margin-right: auto;
    margin-left: 0;
}

input, button {
    margin-top: 10px;
    padding: 5px;
}

#user-list {
    margin-bottom: 10px;
    max-height: 100px;
    overflow-y: auto;
    border: 1px solid #ccc;
    padding: 10px;
    background: #fff;
}

.user {
    cursor: pointer;
    color: blue;
    text-decoration: underline;
    margin-bottom: 5px;
}

#room-list {
    margin-bottom: 10px;
    max-height: 100px;
    overflow-y: auto;
    border: 1px solid #ccc;
    padding: 10px;
    background: #fff;
}

.room-item {
    cursor: pointer;
    color: blue;
    text-decoration: underline;
    margin-bottom: 5px;
}

h3 {
    margin-top: 0;
}