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Warnings appear in the Firefox console even for a blank document. How to avoid some of them?
### Warnings (1):
* Content Security Policy: Couldn’t process unknown directive ‘prefetch-src’ (in Chrome: The Content-Security-Policy directive 'prefetch-src' is implemented behind a flag which is currently disabled.)
### CSS:
* Error in parsing value for ‘-webkit-text-size-adjust’. Declaration dropped. / style.....css:1:109
* Expected declaration but found ‘*’. Skipped to next declaration. / style.....css:1:7859
* Unknown property ‘-moz-osx-font-smoothing’. Declaration dropped. / style.....css:1:41903
* Unknown property ‘-moz-osx-font-smoothing’. Declaration dropped. / style.....css:1:42349
* Unexpected token ‘)’ in media list. / style.....css:1:95166
* Unexpected token ‘)’ in media list. / style.....css:1:97168
* Unexpected token ‘)’ in media list. / style.....css:1:99114
* Error in parsing value for ‘max-height’. Declaration dropped. / style.....css:1:106747
* Error in parsing value for ‘max-height’. Declaration dropped. / style.....css:1:106807
* Unknown property ‘-moz-osx-font-smoothing’. Declaration dropped. / style.....css:1:116056
* Error in parsing value for ‘position’. Declaration dropped. / style.....css:1:116713
* Unknown property ‘-moz-osx-font-smoothing’. Declaration dropped. / style.....css:1:117879
* Unknown property ‘user-select’. Declaration dropped. / style.....css:1:118646
* Error in parsing value for ‘-webkit-text-size-adjust’. Declaration dropped. / worker.....html:4:896
* Expected color but found ‘none’. Error in parsing value for ‘background-color’. Declaration dropped. / worker.....html:4:4147
(*Firefox Dev.Ed. 67.0b16 64bit without add-ons*)
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