--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -199,17 +199,17 @@ pref("extensions.dss.switchPending", fal
 pref("extensions.{972ce4c6-7e08-4474-a285-3208198ce6fd}.name", "chrome://browser/locale/browser.properties");
 pref("extensions.{972ce4c6-7e08-4474-a285-3208198ce6fd}.description", "chrome://browser/locale/browser.properties");
 
 pref("extensions.webextensions.themes.enabled", true);
 pref("extensions.webextensions.themes.icons.buttons", "back,forward,reload,stop,bookmark_star,bookmark_menu,downloads,home,app_menu,cut,copy,paste,new_window,new_private_window,save_page,print,history,full_screen,find,options,addons,developer,synced_tabs,open_file,sidebars,share_page,subscribe,text_encoding,email_link,forget,pocket");
 
 pref("lightweightThemes.update.enabled", true);
 pref("lightweightThemes.getMoreURL", "https://addons.mozilla.org/%LOCALE%/firefox/themes");
-pref("lightweightThemes.recommendedThemes", "[{\"id\":\"recommended-1\",\"homepageURL\":\"https://addons.mozilla.org/firefox/addon/a-web-browser-renaissance/\",\"headerURL\":\"resource:///chrome/browser/content/browser/defaultthemes/1.header.jpg\",\"textcolor\":\"#000000\",\"accentcolor\":\"#f2d9b1\",\"iconURL\":\"resource:///chrome/browser/content/browser/defaultthemes/1.icon.jpg\",\"previewURL\":\"resource:///chrome/browser/content/browser/defaultthemes/1.preview.jpg\",\"author\":\"Sean.Martell\",\"version\":\"0\"},{\"id\":\"recommended-2\",\"homepageURL\":\"https://addons.mozilla.org/firefox/addon/space-fantasy/\",\"headerURL\":\"resource:///chrome/browser/content/browser/defaultthemes/2.header.jpg\",\"textcolor\":\"#ffffff\",\"accentcolor\":\"#d9d9d9\",\"iconURL\":\"resource:///chrome/browser/content/browser/defaultthemes/2.icon.jpg\",\"previewURL\":\"resource:///chrome/browser/content/browser/defaultthemes/2.preview.jpg\",\"author\":\"fx5800p\",\"version\":\"1.0\"},{\"id\":\"recommended-4\",\"homepageURL\":\"https://addons.mozilla.org/firefox/addon/pastel-gradient/\",\"headerURL\":\"resource:///chrome/browser/content/browser/defaultthemes/4.header.png\",\"textcolor\":\"#000000\",\"accentcolor\":\"#000000\",\"iconURL\":\"resource:///chrome/browser/content/browser/defaultthemes/4.icon.png\",\"previewURL\":\"resource:///chrome/browser/content/browser/defaultthemes/4.preview.png\",\"author\":\"darrinhenein\",\"version\":\"1.0\"}]");
+pref("lightweightThemes.recommendedThemes", "[{\"id\":\"recommended-1\",\"homepageURL\":\"https://addons.mozilla.org/firefox/addon/a-web-browser-renaissance/\",\"headerURL\":\"resource:///chrome/browser/content/browser/defaultthemes/1.header.jpg\",\"textcolor\":\"#000000\",\"accentcolor\":\"#834d29\",\"iconURL\":\"resource:///chrome/browser/content/browser/defaultthemes/1.icon.jpg\",\"previewURL\":\"resource:///chrome/browser/content/browser/defaultthemes/1.preview.jpg\",\"author\":\"Sean.Martell\",\"version\":\"0\"},{\"id\":\"recommended-2\",\"homepageURL\":\"https://addons.mozilla.org/firefox/addon/space-fantasy/\",\"headerURL\":\"resource:///chrome/browser/content/browser/defaultthemes/2.header.jpg\",\"textcolor\":\"#ffffff\",\"accentcolor\":\"#d9d9d9\",\"iconURL\":\"resource:///chrome/browser/content/browser/defaultthemes/2.icon.jpg\",\"previewURL\":\"resource:///chrome/browser/content/browser/defaultthemes/2.preview.jpg\",\"author\":\"fx5800p\",\"version\":\"1.0\"},{\"id\":\"recommended-4\",\"homepageURL\":\"https://addons.mozilla.org/firefox/addon/pastel-gradient/\",\"headerURL\":\"resource:///chrome/browser/content/browser/defaultthemes/4.header.png\",\"textcolor\":\"#000000\",\"accentcolor\":\"#000000\",\"iconURL\":\"resource:///chrome/browser/content/browser/defaultthemes/4.icon.png\",\"previewURL\":\"resource:///chrome/browser/content/browser/defaultthemes/4.preview.png\",\"author\":\"darrinhenein\",\"version\":\"1.0\"}]");
 
 #if defined(MOZ_WIDEVINE_EME)
 pref("browser.eme.ui.enabled", true);
 #else
 pref("browser.eme.ui.enabled", false);
 #endif
 
 // UI tour experience.

--- a/browser/components/nsBrowserGlue.js
+++ b/browser/components/nsBrowserGlue.js
@@ -1730,17 +1730,17 @@ BrowserGlue.prototype = {
         return;
       this._openPreferences("sync", { origin: "doorhanger" });
     };
     this.AlertsService.showAlertNotification(null, title, body, true, null, clickCallback);
   },
 
   // eslint-disable-next-line complexity
   _migrateUI: function BG__migrateUI() {
-    const UI_VERSION = 56;
+    const UI_VERSION = 57;
     const BROWSER_DOCURL = "chrome://browser/content/browser.xul";
 
     let currentUIVersion;
     if (Services.prefs.prefHasUserValue("browser.migration.version")) {
       currentUIVersion = Services.prefs.getIntPref("browser.migration.version");
     } else {
       // This is a new profile, nothing to migrate.
       Services.prefs.setIntPref("browser.migration.version", UI_VERSION);
@@ -2137,16 +2137,34 @@ BrowserGlue.prototype = {
       // Now, the sidebarcommand always indicates the last opened sidebar, and we
       // correctly persist the checked attribute to indicate whether or not the
       // sidebar was open. We should set the checked attribute in case it wasn't:
       if (xulStore.getValue(BROWSER_DOCURL, "sidebar-box", "sidebarcommand")) {
         xulStore.setValue(BROWSER_DOCURL, "sidebar-box", "checked", "true");
       }
     }
 
+    if (currentUIVersion < 57) {
+      // Beginning Firefox 57, the theme accent color is shown as highlight
+      // on top of tabs. This didn't look too good with the "A Web Browser Renaissance"
+      // theme, so we're changing its accent color.
+      let lwthemePrefs = Services.prefs.getBranch("lightweightThemes.");
+      if (lwthemePrefs.prefHasUserValue("usedThemes")) {
+        try {
+          let usedThemes = lwthemePrefs.getStringPref("usedThemes");
+          usedThemes = JSON.parse(usedThemes);
+          let renaissanceTheme = usedThemes.find(theme => theme.id == "recommended-1");
+          if (renaissanceTheme) {
+            renaissanceTheme.accentcolor = "#834d29";
+            lwthemePrefs.setStringPref("usedThemes", JSON.stringify(usedThemes));
+          }
+        } catch (e) { /* Don't panic if this pref isn't what we expect it to be. */ }
+      }
+    }
+
     // Update the migration version.
     Services.prefs.setIntPref("browser.migration.version", UI_VERSION);
   },
 
   _checkForDefaultBrowser() {
     // Perform default browser checking.
     if (!ShellService) {
       return;