4.1 Can't centre mobile ads

[Day_]

Not sure why, using the same css as I did in 4.0 but they are stuck to the left, nothing I do will centre them. I'm using

@media screen and (max-width: 767px) {
   #advert_head {min-width: 300px; width: 100%; padding: 0; margin: 0 auto;}
   #advert_foot {min-width: 300px; width: 100%; padding: 5px 0 0 0; margin: 0 auto;}
   #advert_post {min-width: 300px; width: 100%; padding: 0 0 10px 0; margin: 0 auto;}
   #advert_forum {min-width: 300px; width:100%; padding: 0; margin: 0 auto;}
}

Any ideas?

They are centred fine on desktop using

/* LARGER SCREENS */
@media screen and (min-width: 767px) {
   #advert_head {min-width: 728px;  width: 728px; padding: 0 0 15px 0; margin: 0 auto;}
   #advert_foot {min-width: 728px;  width: 728px; padding: 10px 0 0 0; margin: 0 auto;}
   #advert_post {min-width: 728px;  width: 728px; padding: 0 0 15px 0; margin: 0 auto;}
   #advert_forum {min-width: 728px;  width: 728px; padding: 0; margin: 0 auto;}
 }

 

[Day_]

I've added margin: 0 auto; to the adsense code itself and that seems to have worked, I removed the margin from the css as there was no need to repeat it and on desktop they started aligning to the left. Added back in fine. Not sure what's going off there?