mind-overflow-website-ghost-theme/assets/js/scroll-navbar-color.js

var scroll_pos = 0;
var transparent = true;
var offset = 100;

function makeTransparent()
{
  $("#navbar").removeClass('navbar-colored').addClass('navbar-transparent');
  transparent = true;
}

function makeOpaque()
{
  $("#navbar").removeClass('navbar-transparent').addClass('navbar-colored');
  transparent = false;
}

$(document).ready(function() {

  $("#navbar").addClass('navbar-allowmoving');
  scroll_pos = $(this).scrollTop();

  if(scroll_pos > offset)
  {
    makeOpaque();
  }
  else
  {
    makeTransparent();
  }

  $(document).scroll(function() {
    scroll_pos = $(this).scrollTop();
    if(transparent)
    {
      if(scroll_pos > offset)
      {
        makeOpaque();
      }
    }
    else
    {
      if(scroll_pos <= offset)
      {
        makeTransparent();
      }
    }
  });
});