function aufloesung() {
if(screen.width < 1024) {
window.open("popup/popup.htm","projekte","top=0,left=0,toolbar=no,scrollbars=no,directories=no,resizable=no,menubar=no,width=400,height=400");
}
else {
parent.location.href='../projekte/frame.htm';
}
}
<a href="javascript:aufloesung();" target="_parent" class="navi">link</a>
so müsste es gehen
ace