Set the alignment of the gutter renderer. Both xalign and yalign can be -1, which means the values will not be changed (this allows changing only one of the values).
xalign is the horizontal alignment. Set to 0 for a left alignment. 1 for a right alignment. And 0.5 for centering the cells. yalign is the vertical alignment. Set to 0 for a top alignment. 1 for a bottom alignment.