<hr> and header tags work in the new Graal version.
For specifying the color don't use "", just color=#FFFFFF works nicely (you can also use color=red etc.)
<p> tags work for aligning of text
<img> works fine
<font> tag supports options for face, size and color.
Which style options and for which tags do you need? If you see bugs or things not working fine then report it please.