Small styling discrepancies using React with Material-UI in SharePoint Online (non-SPFx)

When I build and publish my React application which uses Material-UI, to SharePoint Online I see a couple of small styling issues. It appears SPO’s styling is being inherited by my Material-UI components in some places and I’m wondering if there’s a way to better isolate them at the application level.

For example, my card action buttons function but are stretched horizontally. card action button

Also, my TextField components still have the nice floating label effect, but get a border around them. textfield elements

Note that this application is not a SPFx project. Thanks for any help!