Table mode: columns resizing due to flex display

During table mode, I've noticed if the amount of data in a column varies a lot in size, the table columns will resize as you scroll up/down making it difficult to follow the table and contents.

I've hacked this with `.jse-modal-contents{ display: block !important; }` which works, but it causes an error in development:

```
ResizeObserver loop completed with undelivered notifications.
at handleError (webpack-internal:///./node_modules/webpack-dev-server/client/overlay.js:252:58)
at eval (webpack-internal:///./node_modules/webpack-dev-server/client/overlay.js:271:7)
```

I would appreciate any pointers to best resolve this!