How to make my Index Gallery Block go top behind my header

Site URL: https://rosedanfordphillips.com/

Hello,

I have a website with a sheer gradient background for my header. I have my index page backgrounds start at the very top of the page, rather than at the bottom of the header, so it looks nice. 

I want to have a full-width gallery block slideshow on my front page, but I cannot work out how to make it start at the top of the page, rather than below the header, as I did with the index background. You can see the difference on my current front page + the work-in-progress page which shows the gallery block. 

Please help!

https://rosedanfordphillips.com/

https://rosedanfordphillips.com/work-in-progress

Add this to Design > Custom CSS

body.homepage .Index-page {
    top: 0 !important;
}