update boostlook.css to new design system

remove high level styles

updated styles for common components; set basic layout margins;

antora and asciidoc templates desktop

antora and asciidoc mobile

commented unused legacy css variables

fixed styles for links in code blocks

Quickbook template adaptation

removed unused css vars

templates specific adjustments; syntax colors

doc/specimen-docinfo-footer.html

@@ -1,6 +1,6 @@
 <style>
 
-*:not(pre)>code { background: none; color: #600000; }
-:not(pre):not([class^=L])>code { background: none; color: #600000; }
+*:not(pre)>code { background: none; }
+:not(pre):not([class^=L])>code { background: none; }
 
 </style>