Postbit сверху сообщений как в vBulletin 3.x

.block--messages .message {
    &.is-mod-selected {border-color: transparent; border-bottom-color: @xf-inlineModHighlightColor;}
}
.blockMessage {box-shadow: none;
    &.blockMessage--none {box-shadow: none;}
}

.block--messages {.block-container {box-shadow: none;}}

.message-inner {display: block;}
.message-cell {
    .m-clearFix();
    &.message-cell--user {
        width: auto;
        border-right: none...