Hello,

Thanks for reaching out to us.

Please use this css in your custom css, You can follow this guide: https://www.joomshaper.com/documentation/helix-framework/custom-code-css-js-meta

@media (max-width: 992px){
header#sp-header div#sp-logo {
    width: 50%;
}
header#sp-header div#sp-menu {
    position: relative;
    z-index: 12;
}
.burger-icon>span {
    background-color: #ffffff;
}
}

Thanks