Change the background colour of one page, which has no header and footer

Hi,
I created a page without header and footer. It looks fine on chrome. However, there is a grey background colour on the top and the bottom instead of white on firefox or mobile. I would like to have a simple white background colour of that page.

I have tried codes like:
.page-id-589 .header_bg, .page-id-589 .container {
background: white;
}

#top.page-id-589 .alternate_color {
background-color: white !important;
}
.page-id-589 .alternate_color.title_container * { color: #white!important; }

However, these codes cannot help to get rid of the grey colour.
May you help me please? Thank you!