In old design, we had 3 column concept - 3 equal columns for source, translation and tools. But in new design @Pginer-WMF proposed connecting the the publishing, saving controls close to the source, translation columns. That means, in new design, we have 2 columns. The first column has 2 column wide header, then source and translation columns. The second column is tools column.
This is the new design
This is illustrated below:
So, in CX2, we should re-arrange the DOM to match the new design instead of relying on CSS styling to achieve new design. I propose to leave CX1 as it is now.