Resizing Eventbrite ticket form iframe on a responsive template

I have embedded Eventbrite's ticket form code on my website successfully, however when it is viewed on mobile, the ticket form does not resize according with the responsive template. i am an amateur in this and have been trying all means to change the coding for the past few hours but to no avail.

Have seek help from Eventbrite but they are unable to give a solution. Is there anyone who can help to solve this problem?

Thank you so much in advance!

The code is as such:

<div style="width:100%; text-align:left;"><iframe  src="www.example.com" frameborder="0" height="1000" width="100%" vspace="0" hspace="0" marginheight="5" marginwidth="5" scrolling="auto" allowtransparency="true"></iframe>
<div style="font-family:Helvetica, Arial; font-size:10px; padding:5px 0 5px; margin:2px; width:100%; text-align:left;"><a style="color:#ddd; text-decoration:none;" target="_blank" href="http://www.eventbrite.sg/r/eweb">Sell Tickets</a> <span style="color:#ddd;">through</span> <a style="color:#ddd; text-decoration:none;" target="_blank" href="http://www.eventbrite.sg?ref=eweb">Eventbrite</a></div>
</div>