Change colour/icon of fields

Hello everyone,

I wanted to change the colour of some fields in the editview and detailview pages of a module.

For example, I have to keep a record of number of blue bags, number of red bags, number of pink bags.

Is it somehow possible to change colour of the field being displayed, or maybe have a small icon next to field name(a tiny square of blue colour etc).

I am trying to do this by changing the css of fields and change the global css for fields, wherever it is written.

Can someone pls tell me how I should go about, whether I am doing it correctly or not?