Your code is not closed properly or correctly formatted. Both would be reasons for the code not applying.
Here is what the code should look like (I’ve added code for center aligning the text):
<p style="line-height:1.5em; text-align:center;">Super Fast and Ridiculously Inexpensive</p>
I’ve closed your code after the last
" to add
</p> would go after the text, if you are wanting to style it.
Once you’ve fixed the code, I’d suggest highlighting the code and removing formatting [Format > Ignore/Clear Formatting].
Let me know if that works!