multiline category labels aren't centered

[dota2heqiuzhi]

In horizontal barcharts with multiline labels (using HTML
tags) the lables are aligned as if they would consist of only one line, i. e. they aren't centered vertically.

[cldougl]

Hi there,
It's not possible to center these labels with Plotly at this time.
You can follow this issue: plotly/plotly.js#1137 in our plotly.js repo (core graphing library) for progress on the feature.