Selectors

<h2>
  Solar System
</h2>
<p>
  The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly.
</p>
<h2 class="heading">
  The Sun
</h2>
<p>
  The Sun is the Solar System's star and by far its most massive component.
</p>
<h2 class="heading">
  Earth
</h2>
<p>
  Earth is the largest and densest of the inner planets, the only one known to have current geological activity, and the only place where life is known to exist.
</p>

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  text-decoration: underline;
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  color: darkblue;
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