I just saw that you are using basel-font-icons for the dropdown arrow in the header menu and simple-line-icons in the sidebar menu. Is there any chance to use just one of them? This would help in terms of page speed optimisations because only one library has to be loaded.
Or even better to use only font awesome. Then I wouldn’t have to load 3 libraries in my frontend. Maybe it would even work to choose which library people want to use.