Selectors

<h2>Earth</h2>
<p>
  Earth is the third planet from the Sun and the only astronomical object known to harbor life. This is enabled by Earth being a water world, the only one in the Solar System sustaining liquid surface water.
</p>

<h2 class="heading">Earth</h2>
<p>
  Earth is the third planet from the Sun and the only astronomical object known to harbor life. This is enabled by Earth being a water world, the only one in the Solar System sustaining liquid surface water.
</p>

/* Write code below */
.heading {
  font-size: 24px;
}