Do not scale line width by line size in AGOL classic map viewer

[EricaNova]

I'm viewing a feature class in AGOL classic map viewer. I've symbolized lines by district and given them all an 8 mm pixel line width. 

However, when I add lines to the map, smaller lines get smaller widths, and larger lines get larger widths. Some of my lines are very short, so they essentially become impossible to see unless you zoom in. See below - very small line for Kemptville Kingston in maroon, and the line width is very small compared to Aylmer Guelph in blue. I want users to be able to see the lines at a provincial scale. I do not want the lines to scale with the line length. If I wanted that, I would have selected that option 🙂

Is there any way to force line width to NOT vary with line length?

Thanks!