added style.css to Style me externally div

[natalietjendera]

Because

This PR

Issue

Closes #XXXXX

Additional Information

Pull Request Requirements

• [ ] I have thoroughly read and understand The Odin Project Contributing Guide
• [ ] The title of this PR follows the location of change: brief description of change format, e.g. 01-flex-center: Update self check
• [ ] The Because section summarizes the reason for this PR
• [ ] The This PR section has a bullet point list describing the changes in this PR
• [ ] If this PR addresses an open issue, it is linked in the Issue section
• [ ] If applicable, I have ensured that the TOP solution files match the Desired Outcome image