How to add Image on apex Command Button ()

To add image in button we need to use below style tag in apex command button tab:-

<apex:commandButton action="{!Export}" value="Export" style="background-image:url({!URLFOR($Resource.SiteSamples,'img/warning.png')});height:25px;width:100px;border-width:0px;background-repeat:no-repeat;cursor:pointer;"/>

                           

Thanks,

Amit Chaudhary