body {
    font-family: sans-serif;
    margin: 0;
    background-color: #f0f2f5;
    transition: background-color 0.3s, color 0.3s;
}

body.dark-mode {
    background-color: #18191a;
    color: #e4e6eb;
}

#app {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

#login-screen {
    text-align: center;
}

#chat-screen {
    width: 80%;
    max-width: 800px;
    height: 90vh;
    display: flex;
    flex-direction: column;
    border: 1px solid #ccc;
    border-radius: 8px;
    background-color: #fff;
}

body.dark-mode #chat-screen {
    background-color: #242526;
    border-color: #3a3b3c;
}

#message-container {
    flex-grow: 1;
    padding: 20px;
    overflow-y: auto;
}

#input-container {
    display: flex;
    padding: 20px;
    border-top: 1px solid #ccc;
}

body.dark-mode #input-container {
    border-top-color: #3a3b3c;
}

#message-input {
    flex-grow: 1;
    border: 1px solid #ccc;
    border-radius: 20px;
    padding: 10px 15px;
    background-color: #f0f2f5;
    color: #050505;
}

body.dark-mode #message-input {
    background-color: #3a3b3c;
    color: #e4e6eb;
    border-color: #3a3b3c;
}

#send-btn {
    margin-left: 10px;
    border: none;
    background-color: #0084ff;
    color: #fff;
    padding: 10px 20px;
    border-radius: 20px;
    cursor: pointer;
}

.hidden {
    display: none;
}

#theme-toggle {
    position: absolute;
    top: 20px;
    right: 20px;
    padding: 10px;
    border: 1px solid #ccc;
    border-radius: 5px;
    cursor: pointer;
}

body.dark-mode #theme-toggle {
    background-color: #3a3b3c;
    color: #e4e6eb;
    border-color: #3a3b3c;
}