slack-custom.css

#msgs_scroller_div::-webkit-scrollbar-track, #client_body::before, .client_container, 
#search_terms, #client_body, #footer, ts-message, .channel_header, ts-jumper ts-jumper-container,
ts-jumper input[type="text"],
.supports_custom_scrollbar:not(.slim_scrollbar) #col_channels:hover #channels_scroller::-webkit-scrollbar-track{
  background: #000 !important;
}

#client_body::before {
  border-bottom: 1px solid #1a2129 !important;
}

ts-message, .channel_title .channel_name, ts-jumper input[type="text"],
ts-jumper ol li .member_real_name, ts-jumper ol li .view_name, ts-jumper ol li .channel_name { 
  color: #eee !important;
  background: #000 !important;
}

.light_theme ts-message .message_content a.message_sender, #msg_input::-webkit-input-placeholder,
ts-jumper input[type="text"]::-webkit-input-placeholder {
  color: #aaa !important;
}

#msg_input, #primary_file_button {
  background: transparent !important;
  color: #eee !important;
  border-color: #444 !important;
}

.day_divider .day_divider_label {
  color: #eee !important;
}

.day_container .day_msgs {
  border-top: 1px solid #1a2129 !important;
}

ts-message:hover, .day_divider .day_divider_label {
  background: #000 !important;
}

#messages_container::after {
  background: #000 !important;
}

.bot_label { 
  padding: 0 4px !important;
  border-radius: 3px !important;
  background: #0a233a !important;
}


.file_container:after{
  background-image: -webkit-linear-gradient(top,rgba(255,255,255,0) 0,#380000 100%) !important;
}

.rxn,
#team_menu,
#col_channels,
#col_channels_footer,
pre,
ts-message .action_hover_container .btn_msg_action,
#messages_container.has_top_messages_banner:before,
.file_container,
.file_container .CodeMirror .CodeMirror-code>div:before, .file_container .CodeMirror .sssh-line:before, .file_container .sssh-code .CodeMirror-code>div:before, .file_container .sssh-code .sssh-line:before,
#col_flex,
.search_message_result,
#flex_contents .heading,
#flex_contents .heading a,
#flex_contents .subheading,
.search_result_with_extract,
#search_filters a,
.menu,
.menu #menu_items_scroller{
  background: #000 !important;
}

pre,
ts-message .action_hover_container .btn_msg_action,
.file_container .CodeMirror .CodeMirror-code>div pre, .file_container .CodeMirror .sssh-line pre, .file_container .sssh-code .CodeMirror-code>div pre, .file_container .sssh-code .sssh-line pre,
.search_message_result .search_message_result_meta a,
.search_message_result .search_message_result_meta .date_links a,
.flexpane_redesign #flex_contents .heading_text,
#flex_contents .subheading,
#search_filters.files #filter_files, #search_filters.messages #filter_messages,
.menu ul li a{
  color: #eee !important;
  /* background: #8f0000 !important; */
}

#quick_switcher_btn{
  border-top-color: #333 !important;
}

.rxn,
.search_result_with_extract,
.flexbox_client.flexpane_redesign.flex_pane_showing #col_flex,
.flexpane_redesign #flex_contents .heading,
#flex_contents .subheading,
.search_segmented_control,
.menu{
 border-color: #000 !important; 
}

.search_result_with_extract {
  box-shadow: 0 1px 10px #555 !important;
}

.comment .mention, .feature_name_tagging_client .comment .mention, .feature_name_tagging_client ts-message .mention, ts-message .mention,
span.match {
  background: #881 !important;
  color: #fff;
}

pre.special_formatting{
  background: #222 !important; 
}

code{
  color: #faa !important;
  background-color: #000 !important;
  border-color: #000 !important;
  font-size: inherit !important;
  font-family: inherit !important;
}

.supports_custom_scrollbar:not(.slim_scrollbar) #archive_msgs_scroller_div::-webkit-scrollbar-thumb, .supports_custom_scrollbar:not(.slim_scrollbar) #msgs_scroller_div::-webkit-scrollbar-thumb,
.supports_custom_scrollbar:not(.slim_scrollbar) #col_channels:hover #channels_scroller::-webkit-scrollbar-thumb{
  background: #000 !important;
}
.supports_custom_scrollbar:not(.slim_scrollbar) #archive_msgs_scroller_div::-webkit-scrollbar-thumb, .supports_custom_scrollbar:not(.slim_scrollbar) #archive_msgs_scroller_div::-webkit-scrollbar-track, .supports_custom_scrollbar:not(.slim_scrollbar) #msgs_scroller_div::-webkit-scrollbar-thumb, .supports_custom_scrollbar:not(.slim_scrollbar) #msgs_scroller_div::-webkit-scrollbar-track,
.supports_custom_scrollbar:not(.slim_scrollbar) #col_channels:hover #channels_scroller::-webkit-scrollbar-thumb, .supports_custom_scrollbar:not(.slim_scrollbar) #col_channels:hover #channels_scroller::-webkit-scrollbar-track{
  color: #000 !important;
}

/*
a, a:link, a:visited{
  color: #a0ccff !important;
}
*/

ts-message a .mention{
  color: #aff !important;
}
a:hover{
  color: #00aef9 !important;
}

.channels_list_holder ul li a.channel_name, .channels_list_holder ul li:not(.unread) .group_name, .channels_list_holder ul li .im_name, .channels_list_holder ul li .mpim_name, .channels_list_holder ul li>a:link,
ts-message a.timestamp{
  color: #aaa !important;
}
#channels_scroller.show_which_channel_is_active ul li.active .im_name,
.channels_list_holder ul li.unread:not(.muted_channel) .primary_action,
#channels_scroller.show_which_channel_is_active ul li.active .primary_action{
  color: #2fbd00 !important;
}

#msgs_div .unread_divider.no_unreads .divider_label{
 background: #000 !important;
 color: #aaa !important;
}

#msgs_div .unread_divider.no_unreads hr{
  border-top-color: #888 !important;
}