Input from engineers would help to determine whether it is better to start with Content Translation, or the new Section Translation first.

Special:ContentTranslation and Special:ContentTranslationStats and section translation mode of Special:ContentTranslation - all use same CX skin. So customization can be done in all pages at once. In other words, doing it in one go is easier than using different styles in CX and SX at same time.

Technically "reuse" is not that easy for skins. Skins are by design independent. So by "reuse" we will require copying the code+styles to CX by keeping the Skin template of CX as such.

In T287743#7311131, @santhosh wrote:

Input from engineers would help to determine whether it is better to start with Content Translation, or the new Section Translation first.

Special:ContentTranslation and Special:ContentTranslationStats and section translation mode of Special:ContentTranslation - all use same CX skin. So customization can be done in all pages at once. In other words, doing it in one go is easier than using different styles in CX and SX at same time.

Technically "reuse" is not that easy for skins. Skins are by design independent. So by "reuse" we will require copying the code+styles to CX by keeping the Skin template of CX as such.

Thanks for the clarifications, @santhosh !
It is good to hear that the update to the skin would benefit both CX and SX.

This styling issues may be related too: T289951: All Echo notifications have underline on Special:ContentTranslation