UX: Make search result styles more consistent (PR #13174)

Search dropdown:

  • Make topic titles use the --primary color like they do everywhere else
  • add a little space between categories and the title (a better match to the main topic list)

Full search page:

  • Reduce the size of topic titles to match the main topic lists
  • Remove a gap between the advanced search title and options below


  • Excerpts on the topic list were displayed as inline, so the top margin was being applied to every line of text. display: block; fixes this, so the margin is only at the top of the excerpt (and space between lines of text is controlled with line-height)