slack.css

.channels_list_holder ul li.mention a, .channels_list_holder ul li.unread:not(.muted_channel) a {
    font-weight: 600;
    color: #EEE;
}

/* remove unread count badge */

.unread_highlight {
    display: none;
}

/* simplify sidebar */

#new_channel_btn, #new_dm_btn, .header_count, #channels_header, #direct_messages_header, #starred_section_header {
    display: none;
}

/* hide team name */

.team_name_container, #presence_container, #team_menu > .notifications_menu_btn {
    display: none;
}

/* hide "edited" postfix of messages */

.edited.ts_tip {
    display: none;
}

/* hide channel top bar icons */

#stars_toggle {
    visibility: hidden
;
}

#channel_calls_button, .channel_title_info > .divider_bar, #details_toggle, #recent_mentions_toggle, #flex_menu_toggle {
    display: none;
}