Answer
If you notice that the lines in the PDF file appear thinner than they should be, it may be because the Line Weights View mode in your Foxit PDF Editor or Foxit PDF Reader is turned off. When Line Weights View is disabled, the lines will be displayed with a constant stroke width (1 pixel), regardless of the zoom level.The following screenshots show the comparison of the PDF file displayed in Line Weights View and Non-Line Weights View.
To resolve this and display the lines with the correct weights defined in the PDF file, follow these steps to re-enable the Line Weights View mode:
Open Foxit PDF Editor or Foxit PDF Reader,go to the View tab>select View Setting,click on Page Display,check the Line Weights option.