Formatting of definition list (CSS)

### Description

The formatting of a definition list ("formatering av definisjonsliste") is missing. All the components in the list have the same format, and this makes the list difficult to read:

It should look something like this (copied from https://interactive-examples.mdn.mozilla.net/pages/tabbed/dd.html):


This example uses a CSS looking like this:
`p,
dt {
font-weight: bold;
}

dl,
dd {
font-size: 0.9rem;
}

dd {
margin-bottom: 1em;
}`

### Additional Information

Discussed on Slack here: https://altinn.slack.com/archives/C068SF24QQM/p1732703663504899

Start by locating the CSS that styles definition lists in the app-frontend-react frontend, then compare the current rendering with the linked MDN example and the CSS shown in the issue. Done means the list visually distinguishes terms from descriptions and adds readable spacing without making all components look identical.

Written by the indexing model from the issue text.