ACleanPlate on "[Theme: Tiny Forge] Tip25b - Remove icon for external sites in child theme"

I'm having a hard time tracking down Tip25b, which promises a method to disable the icons that show up next to external links in a child theme (the style.css of the main theme has a block of CSS you can simply delete). The tip isn't in any of Tiny Forge's files if my search function is working properly. Does anyone have another workaround for this? A block of CSS I could put into my child theme to override the icon's inclusion in the parent theme?

This is the CSS for the icons in the parent theme:

.entry-content a[target=_blank] {
	/* display: inline-block; */
	padding-right: 16px;
	padding-right: 1.142857143rem;
	background: transparent center right no-repeat;
	background-image: url('images/icon-external-link.png');
}

The site I'm working on is http://alt-ternativeautoimmune.com, but the owner has requested it remain private until it is finished.

The tiny forge theme is here: http://wordpress.org/themes/tiny-forge

Appreciate any insight!