Class styling on a custom component in Svelte does not register

I am using Svelte/Sapper templae and added Attractions UI, but I cannot apply any class/styles to their custom components, like so:

<TextField class='search-box' type='search' /><style>    .search-box {        margin-bottom: 10px;    }</style>

I get

Unused CSS selector ".search-box"

The only way to make it work so far for me was to apply the :global modifier on the style.