I thought we had to put units (either px or %) with attribute measurements? Looking at the below code, they don't use any units

Question

<div class="section">
<h1><span>My Media</span></h1>
<iframe height="150" width="300" src="https://www.youtube.com/embed/Q6_5InVJZ88" allowfullscreen frameborder="0"></iframe>
</div>

Answer 1

it's because pixels is the default value if no unit is defined by the user