Refused to apply inline style because it violates the following Content Security Policy directive

Question

So, in about 1 hour my extensions failed hard.

I was doing my extension and it was doing what I pretended. I made some changes, and as I didnt liked I deleted them,

Answer 1

Another method is to use the CSSOM (CSS Object Model), via the style property on a DOM node.

var myElem = document.querySelector('.my-selector');
myElem.style.color = 'blue';

More details on CSSOM: https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement.style

As mentioned by others, enabling unsafe-line for css is another method to solve this.