If you are ever involved in web development using HTML and CSS, Qt's style sheet works exactly the same way as CSS. Style sheets provide the definitions to describe the presentation of the widgets – what the colors are for each element in the widget group, how thick the border should be, and so on and so forth. If you specify the name of the widget to the style sheet, it will change the style of the particular PushButton widget with the name you provide. None of the other widgets will be affected and will remain as the default style.

To change the name of a widget, select the widget from either the form editor or the Object Inspector and change the property called objectName in the property window. If you have used the ID selector previously to change the style of the widget, changing its object name will break the style sheet and lose the style. To fix this problem, simply change the object name in the style sheet as well.