"Nice" is a very subjective concept and can be used to describe people in both complimentary and derogatory ways. In my experience niceness and competence are in no way correlated – I have known nice people who were good at their jobs and assholes who were good at their jobs, as well as some of both who were terrible at their jobs. It is perfectly possible to be both competent and nice.
Given the choice between two persons of equal competence, where one is nice and one is not, I would be surprised if anybody chose the less nice one, all other things being equal.
I suggest continuing to be genuine, rather than focusing on "niceness", and not allowing a single comment on the internet to make you feel self-conscious about your character.
Perhaps you are kind, which is a great way to be. Niceness is artificial, while kindness is a genuine, caring trait. There was a thread on the distinction yesterday: https://news.ycombinator.com/item?id=40696801
One of the biggest problems I run into with Web Components is how to share common CSS styles between them. I understand that goes against the idea that each web component should be encapsulated, but sometimes this is desirable.
Say you have a component library where each component depends on a base set of styles and you don't want to load duplicate styles for each component.
What makes it fast?