Strange boot error

Question

I have been using bootstrap for a long time. Today I notice a strange mistake. I open the mozilla console and there are at least hundreds of errors displayed in twitter-bootsrap source. then I tried to insert bootsrap cdn, but still the same errors. Here is a list of some errors:

Unknown pseudo-class or pseudo-element '-webkit-inner-spin-button'. Ruleset ignored due to bad selector. Expected color but found 'auto'. Expected color but found '-webkit-focus-ring-color'. Expected end of value but found '-webkit-focus-ring-color'. Error in parsing value for 'outline'. Declaration dropped. Expected end of value but found '\9 '. Error in parsing value for 'width'. Declaration dropped. Error in parsing value for 'background-image'. Declaration dropped. 

Is there something wrong with the download?

Answer 1

Some CSS elements have not passed validation in Mozilla, but are accepted in Chrome. The same case with Opera, Safari, especially IE and other browsers. Each browser has different rules that must be followed. Bootstrap and every high-quality CSS must be adapted to all browsers to work properly. Therefore, some elements that you find in consoles as invalid, but in each browser, show different errors.

W3 Validator - only a guide, in fact, the story is completely different.