Use .details-overlay to expand the click area of <summary> to cover the full screen, so user can click anywhere on a page to close <details>.
.details-overlay
<summary>
<details>
Use .details-overlay-dark darken the click area overlay. Useful for modals.
.details-overlay-dark
Use .details-reset to remove the default caret (that little triangle on the left). You then can add the .dropdown-caret on the right of the text.
.details-reset
.dropdown-caret
You can add .btn and .btn-* classes to any <summary> element so that it gains the appearance of a button, and selected/active styles when the parent <details> element is open.
.btn
.btn-*