refactor(docs-infra): remove unused styles for `.heading` CSS class (#40427)
refactor(docs-infra): remove unused styles for `.heading` CSS class (#40427)

This commit removes some styles for the `.heading` CSS class which do
not have any effect (either because they are overridden in other rules
or because they do not make any difference).

NOTE:
The `.heading` class is kept in the HTML to make it easier to associate
the `.heading-children` element with its corresponding `.heading`
parent.

PR Close #40427

mgechev/angular,JiaLiPassion/angular,alxhub/angular,ocombe/angular,JiaLiPassion/angular,brandonroberts/angular,brandonroberts/angular,alxhub/angular,manekinekko/angular,shairez/angular,ocombe/angular,angular-indonesia/angular,brandonroberts/angular,manekinekko/angular,manekinekko/angular,angular/angular,gkalpak/angular,JiaLiPassion/angular,ocombe/angular,alxhub/angular,brandonroberts/angular,mgechev/angular,angular-indonesia/angular,angular/angular,manekinekko/angular,alxhub/angular,shairez/angular,shairez/angular,mgechev/angular,manekinekko/angular,gkalpak/angular,mgechev/angular,gnomeontherun/angular,gnomeontherun/angular,alxhub/angular,ocombe/angular,gnomeontherun/angular,brandonroberts/angular,angular/angular,angular/angular,ocombe/angular,gnomeontherun/angular,JiaLiPassion/angular,mgechev/angular,shairez/angular,manekinekko/angular,gkalpak/angular,angular-indonesia/angular,ocombe/angular,angular-indonesia/angular,brandonroberts/angular,gkalpak/angular,shairez/angular