Perhaps you've got something wrong when you add your wicket markup to it?
Wicket shouldn't do anything with styling your markup unless you use an AttributeAppender or something similar. What I would do is separate things into CSS, HTML, and Java files:
.logo {
background-image: url(images/logo.jpg);
}
.logo td, .logo tr { /* Optional - make sure that table background is seen */
background-image: none;
}
<table wicket:id="myTable" class="logo">...</table>
Alternatively, you could add the logo it in wicket:
WebMarkupContainer myTable = new WebMarkupContainer("myTable");
myTable.add(new AttributeAppender("class", true,
new Model<String>("logo"), " "));
You may also be running into some basic CSS problem, and without more of your HTML markup, it is hard to really help you. But have a look at this question for some ideas.
Personally, I would just wrap the table in a DIV and put the background image in the DIV.