Try spans around the line(s) you want indented.
Code:
<p class="v-ind-rt"> Lorem ipsum dolor sit amet, consectetur adipiscing elit. Suspendisse est ante, <span>venenatis quis arcu nec, hendrerit tempus erat. Mauris varius elit id rhoncus accumsan. Vestibulum imperdiet magna et elit gravida maximus.</span></p>
<p class="v-ind-rt">In non sodales erat. Nam posuere diam sagittis turpis lacinia, nec rutrum metus efficitur. <span>Donec mattis nisi in leo aliquam, eu sodales elit laoreet. Mauris molestie mattis lacus sed facilisis. Maecenas a fermentum turpis, quis dictum mauris.</span></p>
<p class="v-ind-rt">Curabitur a diam ut ante cursus porttitor. Quisque mattis est eget facilisis ornare. <span>Cras aliquet auctor commodo.</span></p>
With this in the css:
Code:
p.v-ind-rt {text-align:right}
p.v-ind-rt span {display:block; margin-right:3em}
Depending on screen size, font size, font style, etc. The lines wont always break at exactly the place you would like, but at least those particular spanned lines would indent.
Here's how it looks in Sigil for both wide screen and small screen:
If it has to look EXACTLY right, then you are stuck with using fixed format or an image.
Cheers!