Ruler rendering: Off-by-one column offset and solid block styling

[dhanoosu]

I am experiencing two visual/functional issues with how the rulers setting is rendered, making it difficult to use as a strict line-length guide.

1. Column off by 1: When configuring the ruler to be at column 80, the highlighted column is offset by one character from the expected boundary (it gets highlighted at column 81).
2. Block rendering instead of a line: The ruler is drawn by changing the background color of the entire character cell, resulting in a heavy visual block. I found no option for this to be rendered as a thin line character (e.g., │) similar to the indentation glyphs - is this possible?