Flash of Unstyled Content (FOUC)
If you use @import alone for external style, sooner or later you'll notice it 'flashes' plain, unformatted HTML briefly before applying CSS in IE.
Adding a LINK element to the basic HEAD element is usually the easiest solution to the FOUC problem.
This issue does not occur when the styles are embedded in the page.
Opera 7+ always shows the Flash Of Unstyled Content for every page that has an @import direcetive. As of this writing there is no solution for a Flash Of Unstyled Content in Opera 7+.
For more information visit:
Flash of Unstyled Content (FOUC) -BlueRobot.