Hat blocks should not overlap in the block pane

[jwzimmer-zz]

We should probably fix this before the playtest on March 16.

Expected Behavior

Hat blocks should not overlap in the block pane.

Actual Behavior

Hat blocks do overlap slightly. @paulkaplan, I think this may have happened when the spacing was reduced between the blocks in #164, scratchfoundation/scratch-blocks#834.

Operating System and Browser

Mac El Capitan & Chrome 56

[jwzimmer-zz]

Moved to scratchfoundation/scratch-blocks#838.