You can still have complete control by using one of the various CSS selectors. For instance, knowing that there is a <span class="Normal"> wrapper, you could use a hierarchical class selector to override any or all attributes of Normal in Text/HTML:
.Normal.MyClass { color: #ff9900; }
Also, descendant and child selectors work well for such situations:
span div.MyClass { ... }
or
span > div.MyClass { ... }
Nik