.introHead	{ margin-top:6.0pt; margin-bottom:6.0pt; text-align:center; font-size:x-small }
.intro	{ font-size:x-small }

<selector class="introHead">
  <property name="margin-top" value="6.0pt"/>
  <property name="margin-bottom" value="6.0pt"/>
  <property name="text-align" value="center"/>
  <property name="font-size" value="x-small"/>
</selector>
<selector class="intro">
  <property name="font-size" value="x-small"/>
</selector>