CSS "and" and "or" and Negation (not) Selectors

Notes on how to implement “and”, “or”, and negation (not) in CSS.

and

<div class="class1 class2"></div>

div.class1.class2

or

// Both apply
<div class="class1"></div>
<div class="class2"></div>

div.class1,
div.class2

not

:not([id="foobar")

ref:

• css selectors - CSS “and” and “or” - Stack Overflow
• html - css class definition with multiple identifiers - Stack Overflow