diff --git a/web/chat/chat-message-list-container.css b/web/chat/chat-message-list-container.css
--- a/web/chat/chat-message-list-container.css
+++ b/web/chat/chat-message-list-container.css
@@ -1,12 +1,9 @@
 div.container {
-  margin-left: 400px;
-  height: 100%;
+  flex: 1;
   background-color: var(--bg);
   display: flex;
   flex-direction: column;
-  box-sizing: border-box;
 }
 div.activeContainer {
-  border: 2px solid #5989d6;
-  margin-left: 402px;
+  border: 2px solid var(--chat-message-list-active-border);
 }
diff --git a/web/chat/chat-tabs.css b/web/chat/chat-tabs.css
--- a/web/chat/chat-tabs.css
+++ b/web/chat/chat-tabs.css
@@ -1,8 +1,5 @@
 div.container {
-  position: absolute;
   width: 400px;
-  top: 0;
-  bottom: 0;
   background-color: var(--bg);
   border-right: 1px solid var(--border-color);
   display: flex;
diff --git a/web/style.css b/web/style.css
--- a/web/style.css
+++ b/web/style.css
@@ -89,9 +89,11 @@
 div.main-content-container {
   position: relative;
   grid-area: app;
+  display: flex;
 }
 div.main-content {
-  height: 100%;
+  display: flex;
+  flex: 1;
 }
 
 div.upper-right {
diff --git a/web/theme.css b/web/theme.css
--- a/web/theme.css
+++ b/web/theme.css
@@ -173,4 +173,5 @@
   --thread-creation-close-search-color: var(--shades-black-60);
   --thread-creation-search-item-bg-hover: var(--shades-black-80);
   --thread-creation-search-item-info-color: var(--shades-black-60);
+  --chat-message-list-active-border: #5989d6;
 }