I use the Developer Tools in IE9 to switch between IE7, 8 & 9 Browser Modes for testing markup & CSS. I use following combinations. IE7 Browser Mode + Document mode IE7 Standards IE8 Browser Mode + Document mode IE8 Standards IE9 Browser Mode + Document mode IE9 Standards But, if i use following combination, few design's position issues are occured. IE9 Browser Mode + IE7 Standards Is the above combination valid? or Does i need to change Document mode forcefully?