At present the box_frame2 shortcode automatically assigns a class named ‘box-frame2’ to all the elements created through this shortcode. How about having a wrapper div around this shortcode so that you can style each box_frame2 uniquely?
[box_frame2 align="center" title="iPhone Hacks" style="width:275px" inner_style="padding:20px;"] ..... [/box_frame2]
Then you can target this box by having .box1 .box-frame2 {}. Better than making a code change. Hope that works for you. Thanks