Ensure dark colors are always used in tutorial hero

[mportiz08]

Bug/issue #, if applicable: 118359891

Summary

Since this component is meant to always be rendered with a dark color scheme regardless of the user chosen setting, there may be some elements (like asides) that may look broken in light mode since they are trying to use light color scheme colors on the dark background.

Example

Before

After

Testing

Steps:

1. Create or update a tutorial with a warning aside in the tutorial intro section
2. Using this branch, open that tutorial page and verify that the warning aside uses the dark colors, even when you choose the "Light" color scheme option
3. Ensure there are no regressions with other colors in this element

Checklist

Make sure you check off the following items. If they cannot be completed, provide a reason.

• Added tests (CSS only change)
• Ran npm test, and it succeeded
• Updated documentation if necessary

[dobromir-hristov]

A bit barbaric 🤣 but we dont have the notion of "themed" components, where we can toggle the light or dark theme on demand, so this will suffice.

[mportiz08]

A bit barbaric 🤣 but we dont have the notion of "themed" components, where we can toggle the light or dark theme on demand, so this will suffice.

Yeah, I kind of hate it lol, but I don't know of a better alternative without explicitly overriding specific colors...which would mean we would end up missing others at some point. Luckily there doesn't seem to be any noticeable performance impact with just redefining all the vars in this way 😅

[mportiz08]

@swift-ci test