[be5invis]

Do you know that all letters in Iosevka are EXACTLY 1/2 em wide?

For ASIAN users, you can use THIS and preserve your perfect alignment.

[Camillo]

So the "m" glyph is half as wide as itself?

[xelxebar]

The em unit is traditionally the width of the letter M, but these days you see it used as the unit height of a font. IIRC, CSS is like this.