Unable to create a link on a H3

Hello!
Im creating a school project and im stuck at creating a link.
When i insert the link, the first H3 element is showing back as a paragraph.
The h3 element shows fine until I insert the link.
There are two other elements identical with the first one where the code works perfect

Here is the full page code:

[metaslider id=78]
<p><strong>Lorem ipsum dolor sit amet, magna fabulas accusata in vix, sit alienum laboramus cu. An causae vocibus torquatos eam. No dignissim euripidis laboramus his, in mel simul accusata reformidans,</strong> id impedit invidunt eam. Commune accommodare mediocritatem ei vix, ea maluisset mediocritatem vix, per ut tollit graecis invidunt.
<br>
Duo ea falli altera salutatus. Regione facilisi nam in, malorum vocibus detraxit mea id, vel ne graece aliquid facilisi. Iisque facilisi nam ne.</p>
<br>

<hr>

<div class="col-md-4">\

<!--//THIS IS THE DIV THAT IS KILLING MY NERVS-->

<a href="http://ceeste.net/category/sanatatebiologie"><h3 class="titluCategorie">Sanatate si Biologie</h3>
<img class="roundImage" src="http://ceeste.net/wp-content/uploads/2016/04/biologie.png"></a>
<p class="paragrafCategorie">Afla cele mai importante informatii din domeniul sanatatii si al biologiei</p>

</div>

<div class="col-md-4">
<a href="http://ceeste.net/category/gadgeturitehnologie/"><h3 class="titluCategorie">Gadgeturi si Tehnologie</h3>
<img class="roundImage" src="http://ceeste.net/wp-content/uploads/2016/04/gadget-300x254.jpg"></a>
<p class="paragrafCategorie">Este de-a dreptul uimitor cat de interesante sunt gadgeturile din ziua de azi</p>

</div>

<div class="col-md-4">
<a href ="http://ceeste.net/category/stiinta/"><h3 class="titluCategorie">Stiinta</h3>
<img class= "roundImage" src="http://ceeste.net/wp-content/uploads/2016/04/Stiinta.png"></a>
<p class="paragrafCategorie">Afla lucruri interesante despre Fizica, Chimie, Univers si multe altele</p>

</div>

Does anyone knows how can i insert the link and make the h3 show normaly?
Thank you!