I would like the main menu to “jump” to mobile mode sooner than it currently does so overlap does not occur (retina display laptop, any browser). I’ve tried several of the quick css suggestions to no avail. Please let me know if you need other information.

max container width – 100%
responsive site – checked
active for smartphones and tablets under 990px

quick css: (tried with and without last css addition)

.avia_cart_buttons .product_type_external {
padding: 11px !important;
background: #ffbe46 !important;
}
.avia_cart_buttons .product_type_external:hover {
background: #95d500 !important;
}
.avia_cart_buttons .show_details_button {
display: none !important;
}
.post-11073 .inner_product_header, .post-11093 .inner_product_header, .post-11106 .inner_product_header, .post-11102 .inner_product_header, .post-11110 .inner_product_header {
margin-bottom: 16px !important;
}
.post-11073 .avia_cart_buttons, .post-11093 .avia_cart_buttons, .post-11106 .avia_cart_buttons, .post-11102 .avia_cart_buttons, .post-11110 .avia_cart_buttons {
padding-bottom: 14px !important;
}
.avia_wpml_language_switch {
display: none;
}
@media screen and (max-width: 599px) and (max-height: 320px) {
.responsive.html_mobile_menu_tablet.html_visible_cart #top .cart_dropdown {
right: 95px !important;
}
}
.language_flag {
display: none !important;
}
.single-product .product {
width: 100%;
}
.single-product-summary {
float:left;
width:45%;
margin-right: 3%;
}
.single-product-main-image {
width: 25%;}
.sidebar {
padding-top: 0px;}
#top.tax-product_cat .product-sorting {display:none;}
.avia_cart_buttons { opacity: 1; }
#top .main_color .avia_cart_buttons .button { color: white; }
.header_color .cart_dropdown_link { background-color: #FFBE46; }
.header_color .cart_dropdown_first .cart_dropdown_link { color: white; }

.single .cart .button { background-color: #FFBE46!important; color: white!important; }

#containerIntro h3,
#containerIntro p {
display: inline;
}
.language_es, .language_en, .language_fr {
display: none;
}
#lang_sel {
height: 75px;
}
.post-meta-infos { display: none; }

.widget {
font-size: 14px;
}

.avia-button.avia-size-large { font-size: 18px; } /* for large buttons */
.avia-button.avia-size-medium { font-size: 18px; } /* for medium buttons */
.avia-button.avia-size-small { font-size: 18px; } /* for small buttons */

.slide-content .blog-categories.minor-meta {
display: none;
}
.avia-button-wrap span.avia_iconbox_title {
font-size: 18px; font-weight: light;
}
.avia-button-fullwidth {
padding: 4px!important;
}
@media only screen and (max-width: 1150px) {
nav.main_menu {display:none !important;}
#advanced_menu_toggle, #advanced_menu_hide {display:block !important; }
}