b-table of BootstrapVue3 is not rendering any ui element

I'm using b-table from bootstrapVue3 https://cdmoro.github.io/bootstrap-vue-3/ but it does not render the UI element.

On github page, it seems b-table is already implemented but I do not know what I am doing wrong.

<template>
  <div>
    <b-table hover :items="items"></b-table>
  </div>
</template>

<script>
export default {
  setup() {
    const items = [
      { age: 40, first_name: "Dickerson", last_name: "Macdonald" },
      { age: 21, first_name: "Larsen", last_name: "Shaw" },
      {
        age: 89,
        first_name: "Geneva",
        last_name: "Wilson",
        _rowVariant: "danger",
      },
      {
        age: 40,
        first_name: "Thor",
        last_name: "MacDonald",
        _cellVariants: { age: "info", first_name: "warning" },
      },
      { age: 29, first_name: "Dick", last_name: "Dunlap" },
    ];
    return {
      items,
    };
  },
};
</script>

renders nothing but text

If I use another component like b-button, it renders as it should. Thank you for your help!