[UI] light mode: csv mapper test result is hardly readable

[aHenryJard]

Description

Environment

1. OS (where OpenCTI server runs): { e.g. Mac OS 10, Windows 10, Ubuntu 16.4, etc. }
2. OpenCTI version: 6.0.10
3. OpenCTI client: frontend
4. Other environment details:

Reproducible Steps

Steps to create the smallest reproducible scenario:

1. Select light mode, all to default (no personalizations)
2. Go to Data > Processing > CSV Mapper (or /dashboard/data/processing/csv_mapper )
3. Create a CSV Mapper
4. Run "test" on it

Expected Output

Be able to read json result to see if the mapper is correct.

Actual Output

Additional information

Screenshots (optional)