Apply suggestion from @estelle

Co-authored-by: Estelle Weyl <[email protected]>

files/en-us/web/css/css_cascade/value_processing/index.md

@@ -35,6 +35,7 @@ Before diving into the individual value stages, it's important to understand the
 - Validates that property values match the expected syntax
 - Eliminates declarations that are syntactically invalid
 
+Only valid declarations become declared values. Declarations with invalid property names or invalid values get filtered out. In this example, only the {{cssxref("font-size")}} and {{cssxref("font-weight")}} declarations are processed. The [CSS parser filters out errors](/en-US/docs/Web/CSS/CSS_syntax/Error_handling#css_parser_errors), ignoring or "filtering" out the declaration with the invalid property name:
 ```css
 /* Valid declarations become declared values */
 p {