Hi Hassan,
You can try to use these css codes to modify the background color of ES's toolbar:
div#fd.es .es-toolbar .navbar-inner{
background: #000 !important;
border: 1px solid #000 !important;
}
div#fd.es .es-toolbar .fd-navbar-search .search-query {
background: #000 !important;
}
div#fd.es .es-toolbar .fd-navbar-search {
background: #000 !important;
}
div#fd.es .es-toolbar .es-toolbar-avatar {
background: #000 !important;
}
You would need to adjust the color(#000) to the ones that you want. Also there are 4 parts of css codes here which corresponds to 4 parts of the toolbar. You can use some or all of them, depending on what you want to achieve.