Denotes an X coordinate alignment in the following formats:
"50%"
"12px"
"center"
"top"
"0%"
"50% - 12px"
"30px - 20%"
"top + 50%"
"center - 12px"
Denotes an X coordinate alignment in the following formats:
"50%")."12px")."center"(which is equivalent to"50%") and"top"(which is equivalent to"0%"))."50% - 12px"and"30px - 20%")."top + 50%"and"center - 12px").