rework and simplify pre, code and listing styles
rework and simplify pre, code and listing styles

benignbala/asciidoctor,anthonny/asciidoctor,asciidocfx/asciidoctor,yukisan/asciidoctor,asciidocfx/asciidoctor,glamouracademy/asciidoctor,gjtorikian/asciidoctor,benignbala/asciidoctor,glamouracademy/asciidoctor,neontapir/asciidoctor,mjang/mj-asciidoc,yukisan/asciidoctor,cuit-zhaxin/asciidoctor,anthonny/asciidoctor,mjang/mj-asciidoc,pepijnve/asciidoctor,pepijnve/asciidoctor,gjtorikian/asciidoctor,cesarmarinhorj/asciidoctor,neontapir/asciidoctor,cuit-zhaxin/asciidoctor