on postback op asp.net coded website @import-ed cssfile is not loaded

Question

We are working on an asp website using frames. In the inner frame, default.css is linked. In default.css, a few css-files are imported. On a postback, the css files are not executed. On a 'normal' load, css is executed.

1. In the source of the webpage we do see the reference to default.css. The path is correct.
2. When using in the head of the webpage, some users have the page displayed perfectly fine, others have a page without css. Those users all use IE, on various OS.
3. viewState true or false does not seem to influence the result
4. FireFox displays the page as intended.

Can you help us look for a solution please?

Answer 1

If the behaviour is consistent i.e. on a specific machine it always load or it never loads, install Fiddler on the failing machine and look into requests and responses. If it fails, these are the possible reasons:
- the browser does not request the CSS file at all (may be a browser bug),
- the browser requests the CSS file, but with erroneus parameters like wrong URL etc (may be your bug),
- the browser requests the CSS file correctly, but the server responds with some error message,
- the browser requests the CSS file correctly, the server responds with the correct CSS file, but it is not used (maybe a browser bug, maybe some obscure browser setting)

If the behaviour is inconsistent i.e. on the same machine and browser sometimes it works, sometimes it doesn't, it most probably is a browser bug (google it) or some weird timing dependency (use fiddler to verify the failing cases).