If the current element does not have a baseline, the bottom of the current element's box should be used. The baseline of the current element box is aligned to the baseline of other superscripted elements in the parent element's box. The baseline of the current element box is aligned to the baseline of other subscripted elements in the parent element's box. This specifies an exact distance to raise or lower the current element from the default 'baseline' value. Positive values are above the baseline, while negative values are below.
Positive percentages are above the baseline, while negative values are below.
The percentage value is relative to the current element's 'line-height' property. It is unknown how this applies to form fields in these versions. Baseline' may also be supported, but all unsupported vertical-align values appear to be rendered as 'baseline' should be. For the Button element, only the value 'super' has any visible effect. Values of 'top', 'text-bottom' and 'baseline' appear to be supported.