Block jitters up and down when hovering over it in chrome.

[monoclex]

In the block selection bar, on Chrome (for me, 87.0.4251.0 (Developer Build) (64-bit)) when hovering under the selected block, it jitters up and down.

As a matter of fact, the blockbar is entirely broken - hovering over other blocks does not nudge them up like it should, nor does their index (the text above them, e.g. `, 1, 2, ..., 0, -, =) change colors (green for selected block, blue for hovered).