Hello There,
Thank you for providing the url. You are into this situation because you are trying to fix the homepage have the menu on top of your slider and yet it affects other pages as well. I would recommend that you update your custom css code and make use of this instead:
.home .masthead {
position: absolute;
width: 100%;
}
And then you will also need to change the menu link color and hover color so that the menu items can be seen when the background is just plain white. You can change it in X > Launch > Options > Header > Link - Text and find the color pickers for the Navbar links and Navbar link hover. You do not have to worry about the color of the menu items in your home page because you can have a different color by using this custom css
.home .x-navbar .desktop .x-nav > li > a,
.home .x-navbar .desktop .sub-menu li > a,
.home .x-navbar .mobile .x-nav li a {
color: #fff !important;
}
We would loved to know if this has work for you. Thank you.