Reducing all that White Space in a SharePoint 2013 Page

Web part pages in SharePoint 2013 render with large spaces between the web part zones. It turns out to be caused by a border-spacing style applied to the ms-webpartPage-root class. Adjusting this to 0px removes lots of the unnecessary white space. Now white space is a Good Thing in design (but in the case of these web part pages it seems to be a little too much of a good thing!). One way is to include the following CSS:

.ms-webpartPage-root { border-spacing:0px !important; }