For the time being, I have created a userstyle: https://userstyles.world/style/12669/community-st-com-condensed
.custom-message-list article.custom-message-tile,
.message-list article.custom-message-tile {
padding: 10px 0;
}
.custom-message-list article.custom-message-tile > footer .UserAvatar > img,
.message-list article.custom-message-tile > footer .UserAvatar > img {
height: 25px;
width: 25px;
}
.custom-message-list article.custom-message-tile > div h3,
.message-list article.custom-message-tile > div h3 {
font-size: 16px;
padding: 8px 0 4px;
}
.custom-message-list article.custom-message-tile > div p,
.custom-message-list article.custom-message-tile > div figure,
.message-list article.custom-message-tile > div p,
.message-list article.custom-message-tile > div figure {
display: none;
}
.custom-message-list article.custom-message-tile > aside,
.message-list article.custom-message-tile > aside {
font-size: 10pt;
}
.custom-message-list article.custom-message-tile > div h3 *,
.custom-message-list article.custom-message-tile > aside *,
.message-list article.custom-message-tile > div h3 *,
.message-list article.custom-message-tile > aside * {
font-size: inherit !important;
}
Preview image of the forum with the userstyle applied