[Broken Website] Power Tools Add-on for Google Sheets

# Broken Website Report

## Website Address
https://docs.google.com/spreadsheets/d/1PvrkqO7KqqRa_36_2mW2MV1fjm-BDZnpYBdR92lHEf0/edit#gid=0

## Steps To Reproduce
- Open a Google Sheets document
- Open the Power Tools side panel

## Expected Behavior
All elements in the side panel would be readable

## Actual Behavior
Some of the elements in the side panel (especially icons) are too dark.

## Screenshots

## System Information
- Windows 10
- Chrome 93.0.4577.63
- Dark Reader 4.9.34

## Additional Context
I have searched the Issues tracker to find a solution. Issues [#4652](https://github.com/darkreader/darkreader/issues/4652) and [#4641](https://github.com/darkreader/darkreader/pull/4641) are similar, but I couldn't find information in those issue threads which solved my problem.