ui: scrollbar am body-rand, todo_write custom renderer

wwwroot/css/main.css

@@ -10,7 +10,7 @@ header {
   flex: 1;
   display: flex;
   flex-direction: column;
-  align-items: center;
+  align-items: stretch;
   overflow: hidden;
 }
 
@@ -19,8 +19,6 @@ header {
   display: flex;
   flex-direction: column;
   overflow: hidden;
-  width: var(--page-width);
-  max-width: 100%;
   transition: var(--transition-duration);
 }
 
@@ -31,3 +29,15 @@ header {
   overflow-y: auto;
   flex: 1;
 }
+
+.page-content:not(.chat-page .page-content) > * {
+  width: var(--page-width);
+  max-width: 100%;
+  align-self: center;
+}
+
+.chat-page .page-content {
+  width: var(--page-width);
+  max-width: 100%;
+  align-self: center;
+}