Change color of close button in bootstrap modal window

Bootstrap is setting the color like this:

.close {
  float: right;
  font-size: 21px;
  font-weight: 700;
  line-height: 1;
  color: #000;
  text-shadow: 0 1px 0 #fff;
  filter: alpha(opacity=20);
  opacity: .2;
}

So you can override it with this:

.close {
    color: #fff; 
    opacity: 1;
}