Modify CSS of specific form

Hello,

I’m looking for a way to modify the CSS of a specific form with a specific id. I know you can add CSS classes to single fields, but is there a way to add CSS classes to forms? Primarily I thought there would be a way to select a specific form by its id in CSS, so I could do something like this:

#form-number-1 .some-class{
color: black;
}
#form-number-1 .some-other-class{
background-color: red;
}

and so forth…

Unfortunately there doesn’t seem to be a way to select the id of a single form in CSS, at least I couldn’t find one.