Port some details of kitchen sink to BS3
Port some details of kitchen sink to BS3

* `btn-large` to `btn-lg` in jumbotron
* add `navbar-default` to first navbar example
rocacua/DIW09,nak-sued-webmasters/theme,rocacua/DIW09,metabrainz/lobes,BBC-News-Labs/bbcnewslabs-bootstrap,timtylin/Heuristically-scholmd-theme,MonkeyDo/lobes,aestrea/aestrea.github.io,dino-poblete/aestrea-www,pthm/bootstrap-amuzor,rocacua/DIW09,bookbrainz/lobes,BBC-News-Labs/bbcnewslabs-internal-bootstrap,aestrea/aestrea.github.io,nak-sued-webmasters/theme,Epick362/themestrap