Coupon code, percentage-based margins

<h1 style="margin: 20px 2% 20px; text-transform: uppercase;">Enjoy 10% Off Your First Order</h1>
<div>
<p style="background-color: #fff; font-size: 24px; border: #983180 dashed 2px; color: #470a68; font-weight: bold; font-family: Gotham,Helvetica,sans-serif; padding: 10px 5px; margin: 20px 2%;">{% coupon_code 'WELCOME' %}</p>
<p style="font-size: 12px; margin: 10px 0 0;"><em>For use on orders of $300 and above. Valid for 7 days only.</em></p>
<br /><br /><a style="letter-spacing: .5px; text-decoration: none; color: #fff; background-color: #000; padding: 20px 55px; font-family: Gotham-Bold,Helvetica,sans-serif; font-weight: bold;" href="{{ organization.url|trim_slash }}/collections/shop-all">REDEEM MY GIFT</a></div>