What dictates max horizontal width and vertical height

[CJVx]

I don’t have a specific meter, I just have a very large string of multi megohm resistors in a divider configuration 100:1. I was worried that it could present a small load on the HV, but there is zero difference in what the picture looks like if I connect it or not, plus the resistors I chose if I remember correctly, probably add up over 100Mohms