- Greater sign
>: means child-direct element. Selects all children-direct element.
Example: div > span
<div>
<span> <!-- filho direto da div -->
DvD
<p>DvD</p> <!-- não é filho direto da div -->
</span>
</div>
- Colon
::: means pseudo-element (a child element).
Example: div::first-letter
Select the first letter within the div (in the case below, the "d").
<div>
<span>
dvd
</span>
</div>
Your example .classe-a::.classe-b{} is incorrect. A class is not
may be a pseudo-element.
Documentation of pseudo-elements in MDN.
- - Sign of
+: selects the element immediately after.
Example: div + p
<div>
dvd
</div>
<p>dvd</p> <!-- este é selecionado, pois está após a div -->
<p>dvd</p> <!-- este não é selecionado -->
- Sign
&: this sign does not exist in CSS. It is used in Sass, a language for compiling CSS codes.
Duplicate of CSS - Selector "::" and What is the difference between the selectors "element element" and "element>element"? and What the + sign in CSS means?
– Guilherme Nascimento
Note: The use of the selector
::in your question this wrong, that does not exist::is for native pseudo-elements - Note 2: The selector&does not exist in CSS, probably it is from Sass– Guilherme Nascimento