Disappearing Thin Lines or Cell Borders
Problem
There are cases where thin lines disappear from the PDF viewer at certain zoom levels.
Cause
This is caused by the limited resolution of the display, while a printer has a superior resolution and there should be no problem printing thin lines on paper.
Solution
If the primary PDF target is the display, then you have to use thicker lines in your CSS customization (for example, avoid using 1px and use 1pt or larger instead).
If you are using Adobe Acrobat Reader, then you can enhance the display of thin lines. This behavior can be changed by going to . Deselecting this option makes thin lines displayed as a row of gray pixels (through antialiasing) and they do not disappear. You can experiment by selecting and deselecting the option.