Question

How do I select a class like class="boolean optional" ?

I have tried this:

.boolean optional {CSS}

.boolean_optional {CSS}

Answer 1

As Zepplock says, that’s actually two classes in a single attribute: boolean and optional. The space is not part of a class name; it acts as the separator.

These three selectors will all match it:

.boolean
.optional
.boolean.optional

The last selector only picks up this element as it has both classes.

You never include a space when chaining class selectors, not even like this:

.boolean .optional

As that selects .optional elements that are contained within separate .boolean elements.