Nothing in CSS - 0 vs 0px, no, none, hidden, initial and unset

<p class="has-line-data" data-line-start="0" data-line-end="1">In this Hasty Treat, Scott and Wes talk about all the nothing in CSS: 0 vs 0px, no, none, hidden, initial and unset.</p> <h2 class="code-line" data-line-start="2" data-line-end="3"><a id= "Show_Notes_2"></a>Show Notes</h2> <ul> <li class="has-line-data" data-line-start="4" data-line-end="5"> <strong><a href="#t=00:22">00:22</a></strong> Welcome</li> <li class="has-line-data" data-line-start="5" data-line-end="6"> <strong><a href="#t=01:50">01:50</a></strong> The @ property</li> <li class="has-line-data" data-line-start="6" data-line-end="7"> <strong><a href="#t=03:33">03:33</a></strong> Hiding Things</li> <li class="has-line-data" data-line-start="7" data-line-end="8"> <strong><a href="#t=10:07">10:07</a></strong> Ghost Spaces</li> <li class="has-line-data" data-line-start="8" data-line-end="9"> <strong><a href="#t=17:47">17:47</a></strong> Collapsing margins</li> <li class="has-line-data" data-line-start="9" data-line-end="10"> <strong><a href="#t=18:33">18:33</a></strong> 0 units vs 0</li> <li class="has-line-data" data-line-start="10" data-line-end="11"> <strong><a href="#t=23:42">23:42</a></strong> Unset and initial</li> <li class="has-line-data" data-line-start="11" data-line-end="13"> <strong><a href="#t=27:42">27:42</a></strong> HTML Bonus</li> </ul> <h2 class="code-line" data-line-start="13" data-line-end="14"> <a id="Tweet_us_your_tasty_treats_13"></a>Tweet us your tasty treats</h2> <ul> <li class="has-line-data" data-line-start="15" data-line-end="16"> <a href="https://www.instagram.com/stolinski/">Scott’s Instagram</a></li> <li class="has-line-data" data-line-start="16" data-line-end="17"> <a href= "https://www.instagram.com/LevelUpTutorials/">LevelUpTutorials Instagram</a></li> <li class="has-line-data" data-line-start="17" data-line-end="18"> <a href="https://www.instagram.com/wesbos/">Wes’ Instagram</a></li> <li class="has-line-data" data-line-start="18" data-line-end="19"> <a href="https://twitter.com/wesbos">Wes’ Twitter</a></li> <li c