Documentation
Publicon
Reference
Preferences
Formatting Options
...Spanning Character Options
SpanLineThickness
• SpanLineThickness is an option for cells that determines the thickness of line-spanning characters such as \[VerticalLine] and \[HorizontalLine].
• With the setting SpanLineThickness 
Automatic, the thickness of line-spanning characters is set to an appropriate default value.
• With the setting SpanLineThickness k, the thickness of a line-spanning character is k times its default thickness.
