@btcbtc: I check in your page and I see that you have added a long “Site Header Text” which is not what you should be doing in this theme. That header section if just for simple headline text and short site header text. That is why you are having a problem.
If you want to add long text then why don’t you create a page and add all your content there then use the “Hero Content” section, from “Appearance => customize => Theme Options => Hero Content” to display that below the header image.