T369636: Fix border misalignment

[medied]

https://phabricator.wikimedia.org/T369636

Follow up to #134. QA feedback pointed to some weird rendering in the corners, after looking very closely I think indeed this border-radius is messing with the correct border rendering.

You really need to get your magnifying glass out to see this one, but I believe this is what was caught by QA:

with border-radius	without border-radius

[medied]

From phab description:

In darkmode, some whitespace is visible at the bottom of the preview

@stephanebisson can you still replicate the above with this branch? If so, could you please provide a screenshot for clarity?

[stephanebisson]

From phab description:

In darkmode, some whitespace is visible at the bottom of the preview

@stephanebisson can you still replicate the above with this branch? If so, could you please provide a screenshot for clarity?

I fixed that part when I continued this work from Huei.

[medied]

CI error seems to be related to npm, it's failing to complete the install and build step. Searching online recommends running npm cache clean --force which I'm trying in 96b00b6 but no luck yet. I can run npm install and npm build commands locally without an issue 🤔

[Nikerabbit]

This is likely webpack/webpack#18963 / nodejs/node#55826