How to make the edges(lines) of the polygon more coherent?

OS (e.g. Win10): win11
PsychoPy version (e.g. 1.84.x):2021.2.3
Standard Standalone? (y/n) If not then what?:y
What are you trying to achieve?:
Hello, everyone!

In builder mode, when I used polygon components to generate polygon stimuli, I found that if the edge of the bold graph is wide, the edge and the edge appear very inconsistent, and the graph is composed of two relatively thick lines at the connection of each two edges. The resulting graph is shown below:

How can I set the edges of the graph to be more coherent, rather than separate, when the edges of the graph are thicker?

One option is two polygons – a smaller solid grey one in front of a solid white one.