I created a new two column template and uploaded the css to the style.css file.  I then went to one of the HTML content modules and copied all the div tags there.  the structure only renders after the page is updated and will not render in the tinymce so working with it is impossible.  Is this by default or am I doing something wrong or placing the css in the incorrect file??

below is the css I am using

<style type="text/css">

.content-block-container {
width: 651px;
vertical-align: top;
}

.content-block-left-header {
padding: 5px 3px 5px 5px;
width: 305px;
float: left;
clear: both;
background-color: #2e3192;
color: #FFFFFF;
font-family: Arial, Helvetica, sans-serif;
font-size: 15px;
}

.content-block-left {
width: 305px;
float: left;
clear: both;
padding-left: 4px;
padding-top: 4px;
padding-bottom: 2px;
font-family: Arial, Helvetica, sans-serif;
font-size: 12px;
color: #000000;
line-height: 20px;
}

.content-block-right-header {
padding: 5px 3px 5px 5px;
width: 305px;
float: right;
background-color: #2e3192;
color: #FFFFFF;
font-family: Arial, Helvetica, sans-serif;
font-size: 15px;

}

.content-block-right {
width: 305px;
float: right;
padding-left: 4px;
padding-top: 4px;
padding-bottom: 2px;
font-family: Arial, Helvetica, sans-serif;
font-size: 12px;
color: #000000;
line-height: 20px;
}

</style>

thanks Joe for responding - let me clarify.

when tinymce is in use I add my div tag with the class and while in edit mode the div tag does not render.  My div tag is simple 200 x 300 with some padding and a background color.  I was hoping that the div would render and so I could enter content into the div box visually while the background, size and padding were shown, but it does not.

the div will only render visually after i save the page.

I have the below div tag in the page
<div class="test-block">testing</div>

I have the below css class in style.css

.test-block{
background-color: #C0C0C0;
font-family: Arial, Helvetica, sans-serif;
font-size: 12px;
width: 200px;
height: 300px;
padding: 10px;
}