room-history: Make read receipts button round when there is a single user

data/resources/style.css

@@ -699,10 +699,10 @@ message-reactions .reaction-count {
 }
 
 read-receipts-list {
-  min-height: 24px;
-  min-width: 16px;
-  padding: 5px 10px;
-  border-radius: 999px;
+  min-height: 20px;
+  min-width: 20px;
+  padding: 6px;
+  border-radius: 9999px;
   transition-property: outline, outline-width, outline-offset, outline-color;
   transition-duration: 300ms;
   animation-timing-function: ease-in-out;

src/session/view/content/room_history/read_receipts_list/mod.ui

@@ -8,6 +8,7 @@
         <property name="spacing">6</property>
         <child>
           <object class="GtkLabel" id="label">
+            <property name="margin-start">2</property>
             <style>
               <class name="caption"/>
               <class name="dim-label"/>