Hi Barrett, thanks for joining the forum.
If you have saved a custom layout in Spinitron then you activate it with layout=1. I don’t think that’s what you need. (Style rules saved in Spinitron are always applied.)
If you want to apply styles to the Spinitron calendar in an iframe, there are several ways to do it described here.
If you don’t understand or have problems, feel free to call me if you prefer.