Rob,
After looking over the code and running it locally, I see that there is some padding on the left that is causing the issue. It looks like it is a padding on the parallax scene shortcode. I would suggest using the code below. The Content Section and Parallax Scene shortcodes are almost duplicates of each other, the main difference is that the Parallax Scene allows for layers of scenes to be stacked upon one another to make layers. The Content Section gives more options and still has the parallax background options. I just changed [intense_parallax_scene] to [intense_content_section] and made a few changes to the centering. Some of the p tags were unnecessary.
[intense_content_section size="full" background_type="image" image="2043" imagemode="parallax" height="600" advance_arrow_background_color="#ffffff"]
[intense_spacer height="60px"]
<center><p><span class="headertitle">Unlimited Potential</span></p></center>
[intense_spacer height="60px"]
<center><p><a style="color: #ffffff; text-decoration: none; font-family: Helvetica, Arial, sans-serif; font-weight: bold; font-size: 16px; line-height: 20px; padding: 10px; display: inline-block; max-width: 300px; border-radius: 5px; text-shadow: rgba(0, 0, 0, 0.247059) 0px -1px 1px; box-shadow: 0px 1px 3px inset, rgba(0, 0, 0, 0.498039) 0px 1px 3px;" href="https://username.leadpages.co/leadbox/145486c73f72a2%3A17f5c2a42b46dc/5675267779461120/" target="_blank">CLICK HERE TO FIND OUT MORE & RECEIVE 60% DISCOUNT</a></p></center>
<script src="https://username.leadpages.co/leadbox-902.js" type="text/javascript" data-leadbox="145486c73f72a2:17f5c2a42b46dc" data-url="https://username.leadpages.co/leadbox/145486c73f72a2%3A17f5c2a42b46dc/5675267779461120/" data-config="%7B%7D"></script>
[intense_spacer height="120px"]
[/intense_content_section]If you need any additional help, please let us know.
Thanks,
Josh