Here is the code I am using for the button right now (with promo code and full URL redacted):
<!-- Noscript content for added SEO -->
<!-- You can customize this button any way you like -->
<style>
.button {
line-height: 1.8em;
font-size: 25px;
color: #fff;
background-color: #3366ff;
border: 2px solid #3366ff;
border-radius: 10px;
padding: 20px 35px;
-moz-transition: all 0.2s;
-webkit-transition: all 0.2s;
transition: all 0.2s;
cursor: pointer;
}
.button:hover {
background-color: #fff;
color: #3366ff;
border: 2px solid #3366ff;
border-radius: 10px;
padding: 20px 35px;
}
</style>
<button id="eventbrite-widget-modal-trigger-eventid" class="button">Register</button>
<script type="text/javascript">
var exampleCallback = function() {
console.log('Order complete!');
};
window.EBWidgets.createWidget({
promoCode: 'code',
widgetType: 'checkout',
eventId: 'eventid',
modal: true,
modalTriggerElementId: 'eventbrite-widget-modal-trigger-id',
onOrderComplete: exampleCallback
});
</script>
</p>