<#if (content.class?exists) > <#include content.class />

This is a JalviewLite Demo Page

<#if (content.alteg?exists) > if you have an up to date version of Java, then
Try the signed applet demos
<#else> Are you are using an old version of Java (pre 1.7.0_51) ?
Try the unsigned applet demos

<#else> ${content.body}