Hello there, @RachelWinters ...
I know that there are certain HTML code snippets that work on a desktop computer, but they will not display in the same manner on a mobile device. Instead, they will display as plain text. (There are also some that will partially work on a mobile device, but they might not display exactly the same as you would see them on a desktop PC.) Here are some of the ones I'm aware of which I confirmed again this morning that, in my opinion, don't work well on mobile:
Alerts
<div class="alert"><strong>Alert:</strong> Sample alert style.</div>
<div class="alert alert-error"><strong>Error:</strong> Sample alert error style.</div>
<div class="alert alert-success"><strong>Success:</strong> Sample alert success style.</div>
<div class="alert alert-info"><strong>Information:</strong> Sample alert info style.</div>
Borders
<div class="content-box pad-box-mini border border-trbl">
<p>some content here</p>
</div>
and
<div class="content-box pad-box-mini border border-trbl border-round">
<p>some content here</p>
</div>
Pills
<ul class="pill">
<li>30% of total</li>
<li>2 Rules</li>
<li>10pts</li>
</ul>
Pop-Up Dialog
<div id="dialog_for_link1" class="enhanceable_content dialog">Bacon ipsum dolor amet pancetta cow...</div>
<p><a id="link1" class="Button Button" style="width: 20%;" title="This is the button description when you roll your mouse over it." href="#dialog_for_link1">Click to Learn More</a></p>
Table (Row Hover)
<table class="ic-Table ic-Table--hover-row">
<thead>
<tr>
<th>Name</th>
<th>Email address</th>
<th>City</th>
<th>State</th>
</tr>
</thead>
<tbody>
<tr>
<td><a href="#">Ella Mentry</a></td>
<td>ella.mentry@gmail.com</td>
<td>Las Vegas</td>
<td>Nevada</td>
</tr>
<tr>
<td><a href="#">Joe King</a></td>
<td>joe.king@gmail.com</td>
<td>Houston</td>
<td>Texas</td>
</tr>
</tbody>
</table>
Tabs
<div class="enhanceable_content tabs">
<ul>
<li><a href="#fragment-1">Tab One</a></li>
<li><a href="#fragment-2">Tab Two</a></li>
<li><a href="#fragment-3">Tab Three</a></li>
</ul>
<div id="fragment-1">Tab 1 content</div>
<div id="fragment-2">Tab 2 content</div>
<div id="fragment-3">Tab 3 content</div>
</div>
Tabs (Color)
<div class="enhanceable_content tabs">
<ul>
<li style="background-color: #acf53d;"><a href="#fragment-1">Tab One</a></li>
<li style="background-color: #c0f56e;"><a href="#fragment-2">Tab Two</a></li>
<li style="background-color: #8eeb00;"><a href="#fragment-3">Tab Three</a></li>
</ul>
<div id="fragment-1">Tab 1 content</div>
<div id="fragment-2">Tab 2 content</div>
<div id="fragment-3">Tab 3 content</div>
</div>
and
<div class="enhanceable_content tabs">
<ul style="background-color: #dcfa70;">
<li><a href="#fragment-1">Tab One</a></li>
<li><a href="#fragment-2">Tab Two</a></li>
<li><a href="#fragment-3">Tab Three</a></li>
</ul>
<div id="fragment-1">Tab 1 content</div>
<div id="fragment-2">Tab 2 content</div>
<div id="fragment-3">Tab 3 content</div>
</div>
I know this might be more than you were asking for, but I thought I'd provide some of the examples I'm aware of for you and others here.
Sing out if you have any questions about this...thanks!