pdf to mobi - mostly happy

Have new paperwhite (4 days :) ). Did one pdf to mobi convert.
I do like the font size and flow. The characters are too light.

I am reading problems with font size and flow issues with convert, so I am not sure if this is minor fix or somehow tied to the font size.

No plugins or tweaks. Just standard pdf to mobi.

I am ok sticking to laptop for my limited pdf's if this is a major issue I'm not seeing.