slack-theme

#add this stuff to the end of "index.js" and "ssb-interop.js" at this location: C:\Users\YOUR_USERNAME\AppData\Local\slack\app-3.3.1\resources\app.asar.unpacked\src\static

// First make sure the wrapper app is loaded
document.addEventListener("DOMContentLoaded", function () {

    // Then get its webviews
    let webviews = document.querySelectorAll(".TeamView webview");

    // Fetch our CSS in parallel ahead of time
    const cssPath = 'https://rawgit.com/albertavery/slack-theme/master/slack-theme.css';
    let cssPromise = fetch(cssPath).then(response => response.text());

    let customCustomCSS = `
   :root {
      /* Modify these to change your theme colors: */
--primary: #09F;
--text: #CCC;
--background: #222;
--background-elevated: #444;
   }
   div.c-message.c-message--light.c-message--hover
   {
   color: #fff !important;
    background-color: #3B4048 !important;
   }

   div.c-virtual_list__scroll_container {
    background-color: #222 !important;
   }
   .p-message_pane .c-message_list:not(.c-virtual_list--scrollbar), .p-message_pane .c-message_list.c-virtual_list--scrollbar > .c-scrollbar__hider {
    z-index: 0;
   }

   div.comment.special_formatting_quote.content,.comment_body{
    color: #ABB2BF !important;
   }

   div.c-message:hover {
    background-color: #3B4048 !important;
   }

   div.c-message_attachment.c-message_attachment{
    color: #7c7b7b !important;
   }

   span.c-message_attachment__pretext{
    color: #7c7b7b !important;
   }

   hr.c-message_list__day_divider__line{
    background: #abb2bf !important;
   }

   div.c-message_list__day_divider__label__pill{
    background: #abb2bf !important;
   }   

   span.c-message__body,
   a.c-message__sender_link,
   span.c-message_attachment__media_trigger.c-message_attachment__media_trigger--caption,
   div.p-message_pane__foreword__description span
   {
       color: #afafaf !important;
   }

   pre.special_formatting{
     background-color: #222 !important;
     color: #8f8f8f !important;
     border: solid;
     border-width: 1 px !important;
    
   }

   // NOT WORKING
   // div.ql-editor.c-message__editor__input {
   //  background: #2c2d30 !important;
   // }
   //
   // div.c-message--light .c-message--highlight .c-message--editing .c-message--highlight_yellow_bg{
   //  background: #3B4048 !important;
   //  border: none !important;
   // }

    `

    // Insert a style tag into the wrapper view
    cssPromise.then(css => {
        let s = document.createElement('style');
        s.type = 'text/css';
        s.innerHTML = css + customCustomCSS;
        document.head.appendChild(s);
    });

    // Wait for each webview to load
    webviews.forEach(webview => {
        webview.addEventListener('ipc-message', message => {
            if (message.channel == 'didFinishLoading')
                // Finally add the CSS into the webview
                cssPromise.then(css => {
                    let script = `
                     let s = document.createElement('style');
                     s.type = 'text/css';
                     s.id = 'slack-custom-css';
                     s.innerHTML = \`${css + customCustomCSS}\`;
                     document.head.appendChild(s);
                     `
                    webview.executeJavaScript(script);
                })
        });
    });
});