Graphics or objects that are anchored to a frame in the document cannot exceed the size of the frame. If you apply a shadow to the borders of an object that fills an entire frame, the size of the object is reduced to display the shadows.
被锁定在文档的某个框中的图形或对象不能超出框的大小。如果对一个填满了整个框的对象的边框采用阴影，则为了显示阴影，对象的大小将会减小。