diff --git a/web/chat/chat-thread-list-item.react.js b/web/chat/chat-thread-list-item.react.js
--- a/web/chat/chat-thread-list-item.react.js
+++ b/web/chat/chat-thread-list-item.react.js
@@ -89,12 +89,13 @@
     [color],
   );
 
-  const sidebars = item.sidebars.map(sidebarItem => {
+  const sidebars = item.sidebars.map((sidebarItem, index) => {
     if (sidebarItem.type === 'sidebar') {
       const { type, ...sidebarInfo } = sidebarItem;
       return (
         <ChatThreadListSidebar
           sidebarInfo={sidebarInfo}
+          isMultipleSidebarItem={index > 0}
           key={sidebarInfo.threadInfo.id}
         />
       );
diff --git a/web/chat/chat-thread-list-sidebar.react.js b/web/chat/chat-thread-list-sidebar.react.js
--- a/web/chat/chat-thread-list-sidebar.react.js
+++ b/web/chat/chat-thread-list-sidebar.react.js
@@ -15,9 +15,10 @@
 
 type Props = {
   +sidebarInfo: SidebarInfo,
+  +isMultipleSidebarItem: boolean,
 };
 function ChatThreadListSidebar(props: Props): React.Node {
-  const { sidebarInfo } = props;
+  const { sidebarInfo, isMultipleSidebarItem } = props;
   const { threadInfo, mostRecentNonLocalMessage } = sidebarInfo;
   const {
     currentUser: { unread },
@@ -39,7 +40,10 @@
       onClick={onClick}
     >
       <div className={css.dotContainer}>{unreadDot}</div>
-      <SidebarItem sidebarInfo={sidebarInfo} />
+      <SidebarItem
+        sidebarInfo={sidebarInfo}
+        extendArrow={isMultipleSidebarItem}
+      />
       <ChatThreadListItemMenu
         threadInfo={threadInfo}
         mostRecentNonLocalMessage={mostRecentNonLocalMessage}
diff --git a/web/chat/sidebar-item.react.js b/web/chat/sidebar-item.react.js
--- a/web/chat/sidebar-item.react.js
+++ b/web/chat/sidebar-item.react.js
@@ -11,10 +11,12 @@
 
 type Props = {
   +sidebarInfo: SidebarInfo,
+  +extendArrow?: boolean,
 };
 function SidebarItem(props: Props): React.Node {
   const {
     sidebarInfo: { threadInfo },
+    extendArrow = false,
   } = props;
   const {
     currentUser: { unread },
@@ -26,6 +28,7 @@
 
   return (
     <>
+      {extendArrow ? <div className={css.threadArrowExtender} /> : null}
       <SWMansionIcon icon="right-angle-arrow" size={28} />
       <div className={css.spacer} />
       <a className={css.threadButtonSidebar} onClick={onClick}>
diff --git a/web/theme.css b/web/theme.css
--- a/web/theme.css
+++ b/web/theme.css
@@ -139,4 +139,5 @@
   --subchannels-modal-color: var(--shades-black-60);
   --subchannels-modal-color-hover: var(--shades-white-100);
   --color-selector-active-bg: var(--shades-black-80);
+  --arrow-extension-color: var(--shades-black-60);
 }