Thanks to Tobias Zimmergren I found out how to add Word Highlighting your Search Result Page. Customizing the Search result page xslt by adding Highlighting What you have to do is to adapt the XSL code in the XSLT Editor of the Core Search Result webpart and locate the the following section (It already exist):
And since this template exists from the beginning, all you really have to do is to customize the style attribute and add a color property of the <b> tag (I replaced it with a <strong> tag instead, for sake of standards) Then you can simply specify the styles for each highlighted word like following:
It’s simple as that. I hope this helped some of you to get started on some basic Search Core Results XSLT customizations. For customizing the result itself you can take also a look at the blog of customize the search result using Sharepoint Designer.