Horizontal alignment of the popover relative to its anchor element.
'auto'
'center'
'end'
'start'
'match-start'
'match-end'
Horizontal alignment of the popover relative to its anchor element.
'auto'— prefers'center'; falls back to'end'or'start'if centering would clip the viewport'start'— popover sits to the left of the anchor (right edge → anchor left edge)'center'— popover is horizontally centred on the anchor'end'— popover sits to the right of the anchor (left edge → anchor right edge)'match-start'— popover left edge aligns with the anchor's left edge (standard dropdown)'match-end'— popover right edge aligns with the anchor's right edge