30% for the name of the prop, especially when addon-controls is enabled is a bit too much:

20% would have been perfect fit. Is there a way to override this somehow?
@domyen can you take a look at this one? i think you might've modified this in the latest round of styling updates
And I think Control column requires some min-width in general or it might end up with something like this:

@shilman got it, will take a look later this week.
Re: column width constraints. This speaks to a larger issue. One of the columns will always get squished when the table is narrow. For instance, in the addon panel. I wonder if we need to hide columns altogether in this case. 馃
So there's another row that is not seen in this screenshot that contained an action with very long type and that what was stretching that column. Maybe it makes sense to put word-break rule on those columns too.
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Maybe simply provide a way to add custom styles to components or the preview/manager pages in general. That's what I personally ended up with, but in somewhat hacky way.
I have a related use case where I'm setting a long url as a default property for an avatar component

The worst part is that it doesn't shrink and creates a horizontal scrollbar when I have dev tools open.
If I add word-break: break-all to the cell through the dev tools it looks fine.

Addressed these issues here in #11805.
If you want to customize the styles further, target these classes:
.docblock-argstable.docblock-argstable-head.docblock-argstable-bodye.g., .docblock-argstable-head th:first-of-type { width: 20% }. Make sure that your selector's specificity is greater than our default styling or use !important.
Whoopee!! I just released https://github.com/storybookjs/storybook/releases/tag/v6.0.0-rc.27 containing PR #11805 that references this issue. Upgrade today to try it out!
You can find this prerelease on the @next NPM tag.
Closing this issue. Please re-open if you think there's still more to do.
Great Caesar's ghost!! I just released https://github.com/storybookjs/storybook/releases/tag/v6.0.12 containing PR #11818 that references this issue. Upgrade today to try it out!