HTML Purifier 4.5.0 is a minor bugfix and feature release, containing an
accumulation of changes over a year.  CSS support has been extended to
support display:inline-block, white-space, underscores in font families,
page-break-* CSS3 properties (when proprietary is enabled.)  We now use
SHA-1 to identify cached definitions, and the semantics of stacked
attribute transforms has changed slightly.