How to remove dash line when hovermode="x unified"

How to remove dash line when hovermode=“x unified”

Like this figure

I have no idea treat this line

Thanks

The following six types of hover mode can be set Select the most suitable setting.

The ‘hovermode’ property is an enumeration that may be specified as:
- One of the following enumeration values:
[‘x’, ‘y’, ‘closest’, False, ‘x unified’, ‘y unified’]