body {
    background-color: #fff; /*default light mode*/
}

.dark-mode {
    background-color: #000; /*dark mode*/
}

form {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    /*form styles*/
}

#dark-mode-toggle {
    position: fixed;
    bottom: 20px;
    right: 20px;
    /*toggle button styles*/
}

#dark-mode-toggle.fixed {
    /*styles when toggle button is fixed*/
}