Does anyone want to take a shot at this Amazon order? Only do this if you are super bored. [View all]

I'm having serious cognitive difficulties today, and nobody here can figure this out. I wrote the company, but did not receive a response.

I'm trying to order a custom size window shade. You have to tell them the size. Sorry for the long link. Explanation is below link.

https://www.amazon.com/Changshade-Cellular-Honeycomb-Darkening-JZCMC-CEL-BG-C/dp/B0GF6BJ91R/ref=sr_1_1_sspa?crid=UGWE9Z19SAO6&dib=eyJ2IjoiMSJ9.G7kw1wtweEETp3iSDmaGVYAZmWVh9yVkN98QMh35CCck4-5JvfmCvfM-i6Ad72F4kDmRB8w8G6tvLQNoPmbGWR-4reOyNuScWR3RsitMAMCWJuXyFmat-5dF2LkgIPkWNVzDItpnGexOl5GVzYVgye7k9hqIwwNet4XoLUXWJ0aohc-xvaj2Ztdg5sL_7Me-bn-Uu59RzWsGTq5SzZP8VOt2kd33TLRODWtw1fPJ2TMu_-Vcx5i2MfmZLy90GhZIUjJikREGCIZs4vtz1c4eNwlVHNcV8Ek4ooZksoooH8s.lKOi_r4BkmyGfZEwuSBhMuGBCDNXZUDUHaJ7DMYmtmY&dib_tag=se&keywords=custom%2Bsize%2Bcellular%2Bshades&qid=1768922638&sprefix=custom%2Bsize%2Bcellular%2Bshades%2Caps%2C153&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1

Go to link
Click customize now (yellow button on right)
Click outside mount
Click window size (NOT shade size)
Under custom width, it says:

Shade width = window width plus 4 inches

My window width is 17 inches (small bathroom window)

Do I order 17 inches and then THEY add 4 inches to equal 21 inches, or do I order 21 inches? I need the width that arrives to be 21 inches in order to partially cover the molding).

I'm not sure which width to report to them the way it is worded.

If you get it right, you get a cookie, (if you pay for the postage plus $20 to cover the cost of my time for typing this shit). But you'll have to convince me that you are correct first.

Thank you, and Godspeed.