Assertion:
The Ruby Text can be positioned above or inline relative to
the main Ruby content with the 'ruby-position' CSS property.
Plain RUBY element, default RT position:
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HTML
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Plain RUBY element, RT position specified with CSS 'ruby-position: above' on RUBY element:
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HTML
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Plain RUBY element, RT position specified with CSS 'ruby-position: inline' on RUBY element:
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HTML
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