Hi @Kelly Chang
So the style you need to change is this:
<style>
#hero .section-dark { background-color: #060606 !important;}
</style>
Its on line 282 of the style.css file.
Rather than editing the css document, if you go to the landing page and then go to the "Landing Page Actions" dropdown in the top left and select "Edit Page Meta Tags" and then in the "Custom HEAD HTML" you can past whatever code you want. The code above will work for you, just change the colour to what you like. See the screen shots below.


Thanks,
Gerard