apply when painting the text,
&#47;&#47;&#47;   in the absence of a `textStyle` being attached to the span.
&#47;&#47;&#47;
&#47;&#47;&#47; * `fontSize`: The fallback size of glyphs (in logical pixels) to
&#47;&#47;&#47;   use when painting the text. This is used when there is no [TextStyle].
&#47;&#47;&#47;
&#47;&#47;&#47; * `height`: The height of the spans as a multiplier of the font size. The
&#47;&#47;&#47;   fallback height to use when no height is provided in through
&#47;&#47;&#47;   [TextStyle.heig