While Princy's solution is correct and will indeed change the background image of the tab container, the complete answer is somewhat longer.
First, which parts of the RibbonBar do you want to change? Apart from the tab container, which Princy already covered, you have the following structure:
- Tab container
- Commands area
With each part being able to have different background.
In addition, in order for the ribbon to have rounder corners in all browsers, we employ a certain amount of nesting to achieve this in terms, the actual selectors may vary.
And finally, there are a couple of skin which are different from the rest e.g. the Metro family skins.
So to properly answer your question, we need to know which skin you want to use (in case it's one of the metro skins) and then which part you would like to customize.
the Telerik team
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