Failed to inline CSS styles in coverage reports

I want to run pytests on a docker container by means of Azure Pipelines.

Given this pipeline snippet:
``` yaml
- job: Test
dependsOn: Build
steps:
- checkout: none
- task: Bash@3
inputs:
targetType: 'inline'
script: |
mkdir $(Build.SourcesDirectory)/reports
chmod 777 $(Build.SourcesDirectory)/reports
displayName: 'Prepare mount folder for reports'
- task: Bash@3
inputs:
targetType: 'inline'
script: |
docker run --rm -v $(Build.SourcesDirectory)/reports:/app/myapp/reports $(image_tag) \
/bin/bash -c 'pytest . --nunit-xml=reports/test-results.xml --cov --cov-report=xml:reports/coverage.xml --cov-report=html:reports/coverage_html --report-dir=reports/coverage_html'
displayName: 'Run PyTest'
```

I get this warning during build:
`##[warning]Failed to inline CSS styles in coverage reports. Error: [Errno 2] No such file or directory: '/home/foo/myagent/_work/3/s/reports/coverage_html'`

The full output is
``` bash

/usr/bin/bash /home/foo/myagent/_work/_temp/4c87c14f-c7ef-42aa-84fd-cd74437fb01a.sh
============================= test session starts ==============================
platform linux -- Python 3.10.13, pytest-7.4.3, pluggy-1.3.0
rootdir: /app/myapp
plugins: azurepipelines-1.0.5, cov-4.1.0, nunit-1.0.4, anyio-3.7.1
collected 4 items

app/test_main.py . [ 25%]
Result Attachments will be stored in LogStore
Run Attachments will be stored in LogStore
##[warning]Failed to inline CSS styles in coverage reports. Error: [Errno 2] No such file or directory: '/home/foo/myagent/_work/3/s/reports/coverage_html'
Reading code coverage summary from '/home/foo/myagent/_work/3/s/reports/coverage.xml'

-- generated Nunit xml file: /app/myapp/reports/test-results.xml ---

---------- coverage: platform linux, python 3.10.13-final-0 ----------
Coverage HTML written to dir reports/coverage_html
Coverage XML written to file reports/coverage.xml

============================== 4 passed in 1.94s ===============================
Async Command Start: Publish test results
Publishing test results to test run '394084'.
TestResults To Publish 4, Test run id:394084
Test results publishing 4, remaining: 0. Test run id: 394084
Published Test Run : https://dev.azure.com/SW4ZF/AZP-352_DivDI_EcoRouting/_TestManagement/Runs?runId=394084&_a=runCharts
Async Command End: Publish test results
Async Command Start: Publish code coverage
Publishing coverage summary data to TFS server.
Lines- 93 of 164 covered.
Branches- 0 of 0 covered.
Modifying Cobertura Index file
Publishing code coverage files to TFS server.
Uploading 18 files
File upload succeed.
Published '/home/infra-admin/myagent/_work/3/s/reports/coverage_html' as artifact 'Code Coverage Report_503679'
Async Command End: Publish code coverage
Finishing: Run PyTest
```

Due to missing inlining of css, the coverage report is broken in AzureDevOps:

I've tried for hours, but can't find a way to fix this warning.

Any help is highly appreciated. Thanks.