Optimizer preview no longer showing results side by side (FF)

[rbayet]

Preconditions

Magento Version : 2.3.1 CE/EE + Firefox

ElasticSuite Version : 2.7.x-dev

Environment : Production

Third party modules : N/A

Steps to reproduce

1. Use Firefox and connect to admin
2. In admin, create a new Optimizer applicable to catalog and/or search
3. Try to preview the optimizer changes

Expected result

1. The preview area shows 2 series of catalog/search results ("Base Results" and "Optimized Results") side by side

Actual result

1. The "Base Results" table is centered and the "Optimized Results" is no longer alongside the "Base Results" but below it.

[rbayet]

Not reproduced on CE/EE 2.2.8 (production mode)

[rbayet]

Not reproduced on CE/EE 2.2.8 (production mode)

Not reproduced on CE 2.2.8 production or developer mode.
Reproduced on CE 2.3.1 production and developer mode (Firefox only).