The atlantic theme v1.0.4 is broken because the ~./zul/css/norm.css.dsp file does not generate, it exists but has size zero.
This causes many aspects of the theme to fail but the most obvious is that all icons disappear.

I downloaded the atlantic source code and ran a package build which confirmed the problem.

Edit src/main/resources/web/atlantic/zul/less/norm.less and comment out the
.verGradient directive around line 412:

.ie8, .ie9, .ie10 {
.z-upload-hover

{ border-color: @hoverBorderColor; // .verGradient(@hoverGradientStart, @hoverGradientEnd); }

}

Now the package build generates a non-empty ~./zul/css/norm.css.dsp and the theme works as expected.

Thus there are 2 bugs:
1. Why norm.less code is failing as above
2. Why the build tools fail silently. Surelly if lessc has encountered an error it should be passing this outwards and causing the maven build plugins to fail?

May also affect other atlantic versions, see:
http://forum.zkoss.org/question/95100/activating-atlantic-theme-removes-icons/