zulip/web/styles/message_edit_history.css

.message-edit-history-container {
    .header-body {
        display: flex;
        align-items: center;
        flex-direction: row;
        justify-content: space-between;
        gap: 5px;

        @media (width < $lg_min) {
            display: block;
        }
    }

    .message-edit-history-list {
        /*
        styles are based on drafts-list
        see web/styles/drafts.css
        */
        & h2 {
            font-size: 1.1em;
            line-height: normal;
            margin-bottom: 5px;
        }
    }

    .message_edit_history_content {
        .highlight_text_inserted {
            color: hsl(122deg 72% 30%);
            background-color: hsl(120deg 64% 95%);
        }

        .highlight_text_deleted {
            color: hsl(0deg 100% 50%);
            background-color: hsl(7deg 90% 92%);
            text-decoration: line-through;
            word-break: break-all;
        }
    }

    .messagebox-content {
        display: block !important;
    }

    #message-history-error {
        /*
        styles are based on .model_content
        see web/styles/modal.css
        */
        font-size: 1rem;
        display: none;
        margin: 10px;
    }
}