Apply style to more than one block

This is a very basic coding question....

I understand how to apply style to a block, using it's Block ID but how do I apply the style to TWO or more Blocks without repeating the code for each one?

So instead of:

div#block-yui_xxx{
  padding-top:0;
}

div#block-yui_yyy{
  padding-top:0;
}

I get something like 

div#block-yui_xxx AND div#block-yui_yyy{
  padding-top:0;
}

Sorry - I found it....

div#block-yui_xxx, div#block-yui_yyy{
  padding-top:0;
}

id1, id2, id3, id4 {your code}