Helena header content and button not responsive

Hello, I'm using the Helena free theme for my website. The header options include a title, content, and a button. I'm choosing to not use a title. Everything looks great on a computer (www.uneventravel.com) but the tablet and phone versions of the header don't show the content and button text, just a grey area where the button text should be. Image responsiveness is fine. Can you please help me get the header content and button text to be responsive? Thank you, Sarah Edit: I tried adding the CSS you recommended in a similar post on Jan 31st but it didn't change anything.