It might be harder to get hold of now, but any of the d20 Star Wars versions could work. Alternatively, d20 Modern with d20 Future tacked on could be familiar enough ground.

What is a sci-fi system that would feel familiar to reluctant Pathfinder players?
I would like to make my webpages a w3c valid.so i rectifying the errors step by step to be valid , i used html5 doctype, I found an error 

Line 348, Column 81: RDFa Core attribute rel is not allowed on the li element in HTML5 + RDFa 1.1 Lite documents. Consider checking against the HTML5 + RDFa 1.1 schema instead.

so i tried to replaced id instead of rel , w3c valid but the code doesn't work . How to work the below code without using rel?

&lt;script type="text/javascript"&gt;
$(document).ready(function() {
$(".tab_content").hide();
$(".tab_content:first").show(); 
$("ul.tabs li").click(function() {
    $("ul.tabs li").removeClass("active");
    $(this).addClass("active");
    $(".tab_content").hide();
    var activeTab = $(this).attr("rel"); 
    $("#"+activeTab).fadeIn(); 
});
});
&lt;/script&gt; 
&lt;ul class="tabs"&gt;
&lt;li class="active" rel="tab2"&gt;&amp;nbsp;&amp;nbsp;Reviews&amp;nbsp;&amp;nbsp;&lt;/li&gt;&lt;li rel="tab3"&gt;News&lt;/li&gt;&lt;li rel="tab4"&gt;&amp;nbsp;&amp;nbsp;Articles&amp;nbsp;&lt;/li&gt;&lt;/ul&gt;


&lt;div id="tab1" class="tab_content" style="width:326px;"&gt;data&lt;/div&gt;
&lt;div id="tab2" class="tab_content" style="width:326px;"&gt;data tab2&lt;/div&gt; 

