Navigation header invisible when scrolling up

Site URL: https://sealion-guitar-cn6h.squarespace.com/config/design/custom-css

hi guys/girls,

I have a brine template. The navigation is normally not visible when scrolling up and down. I put custom css for navigation header so that it's visible when scrolling up but now it's also visible when scrolling down. Can somebody tell me how I can turn that off when scrolling down?

this is the custom css now for the header:

 

/* begin semi-transparent and fixed header */

  @media screen and ( min-width: 641px ) {
  
    /* order of rule-sets is important */
    
    .sqs-announcement-bar-dropzone,
    .Header--top
    
      {
      
      position: fixed;
      width: 100%;
      z-index: 99;
      
      }
      
    .sqs-announcement-bar-dropzone {
    
      top: 0;
      
      }
      
    .Header--top {
    
      background: rgba( 0, 0, 0, 0.7 );
      top: 36px;
      
      }
      
    .Header-inner--top {
    
      padding-bottom: 16px;
      
      }
      
    .Site-inner {
    
      margin-top: 225px;
      
      }
      
    .homepage .Site-inner {
    
      margin-top: 36px;
      
      }
    }
    
  /* end semi-transparent and fixed header */

Hi. Do you still need help on this? If yes, can you share access password?  We can check easier