PHP cURL strange behavior

It changes font color from #fff to #818181

[wildbest]

Original code is something like this:

style="text-decoration:none;color:#fff; font-size: 12px;"

And when cURL-ed it is changed to:

style="text-decoration:none;color:#818181; font-size: 12px;"

Any idea what might cause this change?

[rocknbil]

Is it possible the host is serving a different page via curl than the public page? Are there any other content differences?