This REPLACE statement adds to the child style definition the style element titlesandfooters, which also exists in the parent style definition. The new definition does not inherit attributes from any style element, but it will pass its attributes to any style element that inherits from titlesandfooters or from a child of titlesandfooters. This style element uses systitlefg and systitlebg for colors, but it changes the font size from the one specified in titlefont2 (4) to 3. As a result, the titles and footnotes in HTML Output from PROC PRINT with the Customized Style Definition are smaller than the ones in HTML Output from PROC PRINT with the Default Style Definition. 
   replace titlesandfooters /
      foreground=colors("systitlefg")
      background=colors("systitlebg")
      font=fonts("titlefont2") font_size=3;