Conflicting Header CSS

Site URL: https://magnolia-shark-g9jd.squarespace.com/

I've set up the header to be transparent on header images and on scroll it turns dark blue. On blog pages I need the header to be blue before scroll. Something in my CSS is conflicting and I've fiddle around with removing the important tag but I can't figure out how to make the code not conflict.

Password to the site is: fiossftw

Here's the CSS I'm using:

.Header, Main Main--blog-item {
  background: hsla(202, 100%, 27%,.9)!important;
  position: fixed!important;
  z-index: 1000;
  width: 100%;
    padding-bottom: 15px;
}

.Header {
  background: hsla(202, 100%, 27%,.0)!important;
  position: fixed!important;
  z-index: 1000;
  width: 100%;
    }

.Header.scrollNav {
  background: hsla(202, 100%, 27%,.9)!important;
  padding-bottom: 15px;
}

Thanks in advance for any guidance. 

What is access password?

this code for?

.Header, Main Main--blog-item {
  background: hsla(202, 100%, 27%,.9)!important;
  position: fixed!important;
  z-index: 1000;
  width: 100%;
    padding-bottom: 15px;
}

@tuanphan the access code is "fiossftw"

That code is for making the header blue on blog pages only (without having to scroll)

.Header is Header Class Name

Main Main--blog-item IS NOT BLOG HEADER CLASS NAME

Ok thank you! How would I target just the blog page header to be blue before scroll?

@tuanphan Any guidance on how to target just blog headers?