packages/charts/src/components/icons/_icon.scss

.echIcon {
  flex-shrink: 0; // Ensures it never scales down below it's intended size
  display: inline-block;
  vertical-align: middle;
  fill: currentColor;

  svg {
    transform: translate(0, 0); // Hack to fix Firefox "softness"
  }

  &:focus {
    opacity: 1; // We often hide icons on hover. Make sure they appear on focus.
    background: $euiFocusBackgroundColor;
  }
}