Random background disappearance?

[TrMako]

Alright, so I have a simple assignment for a class to make a checkout form for a sample donut shop. The prof likes colors and neatly organized stuff using divs. What I can't figure out for the life of me, is why sometimes when I input invalid data (such as negative numbers, decimal numbers, or alpha characters) into the quantity text boxes, the page reloads with a random chunk of the background fill color missing. And to top it off, if I highlight the missing area by just clicking and dragging my mouse, the color comes back. The url for the page is: http://classweb2.mccombs.utexas.edu/mis333k-byars/msbbd883/asp1/checkout.aspx if you want to check it out I'd greatly appreciate it. Like I said, the problem only seems to occur when you press calculate while there is invalid data in one of the quantity fields. If you want to view the css file along with it just go to http://classweb2.mccombs.utexas.edu/mis333k-byars/msbbd883/asp1/stylesheet.css
Thanks.

[Fang]

Not seeing the problem.

[Ferret]

Seems to work for me as well. I entered -1 into the box and it shot an error message, "please enter a positive integer etc etc"

[TrMako]

Thanks for looking at it. I have no idea what changed but it doesn't seem to be doing it anymore.

[Major Payne]

Very well done, too. Works like a charm. Only a couple of coding errors:

HTML Validator result
----------------------
http://classweb2.mccombs.utexas.edu/mis333k-byars/msbbd883/asp1/checkout.aspx

line 12 column 1 - Warning: <input> ID "__VIEWSTATE" uses XML ID syntax
line 106 column 2 - Warning: <input> ID "__EVENTVALIDATION" uses XML ID syntax
Info: Doctype given is "-//W3C//DTD XHTML 1.0 Transitional//EN"
Info: Document content looks like XHTML 1.0 Transitional
0 errors / 2 warnings

An ID attribute does not conform with the HTML document type specification. ID tokens must begin with a letter, and may contain only letters, digits, hyphens, underscores, colons, and periods.
Example:

<li> ID "_note-0" uses XML ID syntax

Ron