Placing Twitter button in IE7+ versus Firefox

[TWood]

I created a DIV class as shown next to contain the code for a Tweet button that I placed in the 'postbit_legacy' template in the header bar DIV that is called 'posthead'.

.posttwitbutton {
display: inline;
margin-left: 2px;
}

The display: inline; works for Firefox, but not for IE7.

Firefox:

https://vborg.vbsupport.ru/external/2011/06/49.png

IE7:

https://vborg.vbsupport.ru/external/2011/06/50.png

How can I get IE7 to place the button horizontally 'inline' in the post header so it looks like Firefox?