Hi, I created three classes within the ID#Content that will each hold an image but they are not showing up?

Code HTML4Strict:
<div class="symbol_visual">
<div class="symbol_create"></div>
<div class="watch"></div>
</div>

Code CSS:
.symbol_visual {
	width:250px;
	height:250px;
	color:gray;
	border: 1px;
	z-index:1;
 
}
There is presently only a style for one of the classes.