Inserting PNGs and retaining transparency

Hello everyone,

For a PNG image with transparency, placed in the WordPress HTML editor, is there a way to place a tag around the code so that the transparent portions are NOT automatically filled in by WordPress?

If I am understanding my problem correctly, WordPress is automatically filling in my PNG images placed in the middle of pages.

I am trying to place PNG images onto my WordPress page, without a border, and with transparent areas still transparent.

I have removed the border around JPEGs and PNGs with this code:

CSS insert:

/* Optional images with no borders */
.customImage img {
padding: 0px;
border: none;
-moz-border-radius: 0px;
-khtml-border-radius: 0px;
-webkit-border-radius: 0px;
border-radius: 0px;
}

And I use it like this when I don’t want a border:

<div class=”customImage”>
— JPG or PNG image code here —
</div>

So I can remove the border around the PNG, but not retain the transparency.

You can see my page here to illustrate:
http://roadreview.net/roads/united-states/california/latigo-canyon/

How do I insert a PNG image and retain the transparency?

Thank you very much for your time, I appreciate it.