code: @Nonnull
    public static String getRewrittenCSS (@Nonnull final String sOriginalCSS, @Nonnull final CSSWriterSettings aSettings)
    {
      ValueEnforcer.notNull (sOriginalCSS, "OriginalCSS");
      ValueEnforcer.notNull (aSettings, "Settings");
  
      final CascadingStyleSheet aCSS = CSSReader.readFromString (sOriginalCSS, aSettings.getVersion ());
      if (aCSS != null)
      {
        try
        {
          return new CSSWriter (aSettings).getCSSAsString (aCSS);
        }
        catch (final Exception ex)
        {
          LOGGER.warn ("Failed to write optimized CSS!", ex);
        }
      }
      return sOriginalCSS;
    }
docs: Get the rewritten version of the passed CSS code. This is done by
  interpreting the CSS and than writing it again with the passed settings.
  This can e.g. be used to create a compressed version of a CSS.
  
  @param sOriginalCSS
  The original CSS code to be compressed.
  @param aSettings
  The CSS writer settings to use. The version is used to read the
  original CSS.
  @return If compression failed because the CSS is invalid or whatsoever, the
  original CSS is returned, else the rewritten version is returned.