Question: I want to remove the default autocomplete from all input fields of my web application using CSS only. I will put that CSS in the header of my web application to get the effect of that css on all web pages. I can't put `autocomplete=off` in all input fields individually. as there are more than 200 input in the application.

Answer: 
It is not possible since `autocomplete=off` is not a css attribute, but a html5 one.

Maybe you want to do it with js by setting element's `attr`, or just find and replace those 200 entries once and for all.

More info on `autocomplete=off` [can be found in MDN](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input#attr-autocomplete).
It's not possible in CSS. You can achieve it by using JS.