Applying the below code:

$('<div>Reward:<br />' + sym + item.reward + '</div>')
.css({
fontSize: '80%',
width: '33%',
styleFloat: 'left',
backgroundColor: '#ff6',
backgroundRepeat: 'none',
textAlign: 'center',
display: 'none'
})
.addClass('reward')
.appendTo('#question-' + item.id);

This causes an error in IE7, line 906:

Error: Could not get the backgroundRepeat Property. Invalid argument. This error actually appears to be in the .attr() function in jQuery.js:

if ( value != undefined ) elem[name] = value;