Add a css class "lightTheme" to the body, so that we can set the css style...

Add a css class "lightTheme" to the body, so that we can set the css style based on the current light theme

e.g. in css you can do:

/* For dark theme */
.hello {
   color: green;
}

/* For light theme */
body.lightTheme .hello {
   color: red;
}