Figured it out--needed to make a second sheet on which to place the filled contours, placed below the Land sheet in the drawing order. Then select colour, change properties on the contour, select the colour, "fill style solid", "line style solid", and "move sheet" to the filled contour sheet, which was set to hidden so it would disappear on each redraw, leaving just the unfilled contours. Change colour, repeat, and got there!

I cheesed on the frame--just made a huge rectangle over the whole map with the rectangle tool, changed properties (line width to 250), and outlined in black

😁

Here's the result

Think I figured it out...

Thank you, everyone! This forum is filled with such amazing people. I appreciate all of you!

Her styles definitely seem to have a unifying artistic theme that I really love!

Absolutely love what you've been doing! I haven't build a sewer yet but found I quite enjoy using the arches in other sets--I added them in to an underwater temple I'm working on. Here's a detail of it.

Are you matching your sewer system to a street plan of one of your cities?