Make clearer categories for the movies on the 'about' page

data/public.md

@@ -21,11 +21,15 @@ planets, galaxies, or even the whole universe. We do this to test theories
 about what the universe is made of and how it evolved from the Big Bang up to
 the present day!
 
+#### Cosmological simulations
+
 <div class="videowrapper"><iframe width="100%" height="100%" src="https://www.youtube.com/embed/DF2FV4HiVBU" frameborder="0" allowfullscreen></iframe>
 </div>
 The formation of the Perseus cluster of galaxies recreated within
 the SIBELIUS-DARK simulations.
 
+#### Planetary simulations
+
 <div class="videowrapper"><iframe width="100%" height="100%" src="https://www.youtube.com/embed/AQmeomxvokM" frameborder="0" allowfullscreen></iframe>
 </div>
 A simulation of a plausible formation scenario for the moon as the