Fix CSS formatting

Problem/Motivation

The current CSS file has most of the code in single line that makes it less readable. e.g.
.rn-overlay input.rn-filter{background:#222;border:1px solid #333;color:#fff;padding:6px 28px 6px 8px;border-radius:4px;min-width:260px}

Steps to reproduce

Validate the css file at /assets/css/reviewer_notes.css

Proposed resolution

Make this CSS file more readable and format it.

Remaining tasks

Format this CSS file and raise the PR.

User interface changes

N/A

API changes

N/A

Data model changes

N/A