How do I override user agent defualts?

Hi.

Google Chrome defaults override any setting of mine regarding p tag, unless I override in each contect. Thas is:

p{
  margin: 0; 
}

does not work, while

.view-product-accessories{
  p{
	margin: 0;
  }
}

does work.

I would like to avoid repeating this for every context, of course. Using a mixin is not an elegant soution. Any ideas?

Thanks!