I updated to the latest MaterializeCSS and my modals and collapsibles now have a blue border around them. You can see this issue here when you click the "Modal" button: http://materializecss.com/modals.html


it's an outline when the object is focus.
You can override this on CSS with:
<style type="text/css">
.modal:focus, .dropdown-trigger:focus{
outline:none!important
}
</style>
Looks like the fix (for collapsibles at least) should be in the next release.
As an interim fix, per @asdfprah's suggestion, be sure to add .collapsible-header:focus.
Fix:
https://github.com/Dogfalo/materialize/commit/4e7495368c54943b60688635f723ec9e9592521a#diff-eb64e6e2ac7c9f7a778c8b27643df12d
That fixed it. Thank you both!
Most helpful comment
it's an outline when the object is focus.
You can override this on CSS with: