I think what is happening is you are using 1.5 but the demo is 1.0. Joomla places Headers <H1>, <H2>, etc for contentheaders in 1.5 but it didn’t in 1.0 (Feel free to correct me here if I’m wrong anyone?)
It would appear Joomlart did not quite update the css when they updated Iris to 1.5.
So.. what you need to do is open template.css and find…
/* Heading */
h1 {
font-size: 180%;
}
h2 {
font-size: 150%;
}
h3 {
font-size: 135%;
}
h4 {
font-size: 100%;
text-transform: uppercase;
}
….. and change it to suit your needs. Maybe something like…
/* Heading */
h1 {
font-size: 120%;
}
h2 {
font-size: 110%;
}
h3 {
font-size: 105%;
}
h4 {
font-size: 100%;
text-transform: uppercase;
}