Can't set selection box color through global theming

[DanielSidhion]

I've been trying to set the selection box color using the global theming structure as described here.

However, it looks like the selection box color is always overridden by Svelvet:

• The Svelvet component defines a selectionColor here, which gets passed to Graph.
• selectionColor ends up passed to SelectionBox. Even though SelectionBox allows its color to be null, neither Svelvet nor Graph allow that, so an actual value will end up getting passed.
• SelectionBox's color property ends up used in --prop-selection-box-color here, and that takes precedence over the --selection-box-color property suggested by the styling guide on Svelvet's website.

Basically, this means that the only way to properly customize the selection box color is by passing it through a prop. I'd like to avoid that, as I'm using Tailwind CSS in my project, and I'd like to just use the values from Tailwind like the following:

:root[svelvet-theme='my-custom-theme'] {
    --selection-box-color: theme(colors.purple.500);
}

theme() is a Tailwind construct that pulls the value straight from the Tailwind theme. I could just figure out what value it is that I'm currently using and copy that value in Svelvet's selectionColor prop, but whenever I change the color in my project, I'll have to remember to also update the prop.

Do you folks have any suggestion on how to fix this? I'm willing to submit a PR, but I'd like to know if there's a preferred way to solve this. My suggestion would be either changing the precedence order here and here to consider --seelction-box-color first, or allow undefined or null in Svelvet and Graph's selectionColor prop.