I have a few buttons on my html page created like this:
<button type="button" class="read-more"><a href="#">Read More</a></button>
<a href="#"> <button type="button" class="read-more">Read more</button></a>
Your HTML is invalid. Use a validator. A button cannot contain an anchor and an anchor cannot contain a button. Different browsers recover from that error in different ways.
Then apply CSS to make it look the way you want.