2.1.682 Part 4 Section 18.104.22.168, sheetView (Worksheet View)
a. The standard states that the values of the colorId attribute are defined by the XML Schema unsignedInt datatype.
Office restricts the colorId attribute value to an unsignedInt less than or equal to 64.
b. The standard specifies that the @colorId defines the color value for text in row/column headings and gridlines in the view.
Office uses the @colorId to define the color value only for gridlines in the view.