OK, changed the css to:

h1 {
margin: 0;
font-family: Arial, Helvetica, sans-serif;
color: #FF6633;
font-size: 20px;
display: inline;
}

.h1subheading {
font-family: Arial, Helvetica, sans-serif;
color: #FFFFFF;
font-size: 11px;
}

but it still doesn't look right in IE