how to apply color to particular character of string component using css

General
1

how to apply color to particular character of string component using css

2

You can’t, if they are in the same DOM element. You need to split up the content you want to style like this:

Label styledLabel=new Label();
styledLabel.setContentMode(ContentMode.HTML);
styledLabel.setValue("This label is otherwise normal, except for the <span>color</span>");

then you can use CSS to theme that particular part of the label:

.v-label-thatparticularlabel span {
    color: green;
}