The multi toggle responsive navigation on smaller screens is similar to nested accordions, the user touches primary level parent item to reveal list under it and when the screen is big enough vertical toggle menu changes to horizontal drop down navigation.
If you are making a custom Content Management System (CMS) then responsive, almost pure CSS, admin template is for you. It is built with Bootstrap and provide functionality and ease of use at the same time.
Amplify is free full featured accelerated mobile pages (AMP) template. It is a simple HTML template for Jekyll and static website or blog.
SingleApp is a beautiful free single page highly responsive WordPress theme. It can be converted into a full blown web blog. But it is ideally for business that just want make an impressive landing page for their product.
ngx-admin is the next version of the famous ng2-admin - Angular 2 Admin Panel. This version is built with Angular 4, Bootsrap 4 and Typescript. It is recommended to use ngx-admin for all future developments as ng2-admin can not be upgraded to ngx-admin.