Incorrect line height with canvas

[mofux]

Look at the screenshot. Notice the cyan border. In xterm.js (top picture), there is a visible gap between the | strokes. With lineHeight set to 1, I would expect the output to look exactly as in Terminal.app (bottom picture). I think this is caused because we Math.ceil the measured character height.

[Tyriar]

I think this is related to the default font. Both these work great:

term.setOption('fontFamily', 'Fira Code')
term.setOption('fontFamily', 'Hack')