Presets comes with a built-in layout that works out of the box.
And there are some ways to customzie the layout/theme.
If you need third-party front-end libraries to achieve some functions, you can inject them via the ExtraAsset method, and they will be automatically served.
you can also call Injector in AssetFunc to add meta, add custom HTML in HEAD and TAIL.
You can change the entire layout via LayoutFunc. The default layout is https://github.com/qor5/admin/blob/1e97c0dd45615fb7593245575ab0fea4f98c58b3/presets/presets.go#L860-L969
We also provide some options to tweak the layout
And We provide PlainLayout which has no UI content except necessary assets. It will be helpful when there are some pages completely independent of Presets layout but still need to be consistent with the Presets theme.