Initialize line-height for room name on IRC layout (#10188)

cypress/e2e/timeline/timeline.spec.ts

@@ -161,6 +161,9 @@ describe("Timeline", () => {
                 "created and configured the room.",
             ).should("exist");
 
+            // Check room name line-height is reset
+            cy.get(".mx_IRCLayout .mx_NewRoomIntro h2").should("have.css", "line-height", "normal");
+
             cy.get(".mx_MainSplit").percySnapshotElement("Configured room on IRC layout");
         });
 

res/css/views/rooms/_IRCLayout.pcss

@@ -23,6 +23,12 @@ $irc-line-height: $font-18px;
 
     line-height: $irc-line-height !important;
 
+    .mx_NewRoomIntro {
+        > h2 {
+            line-height: initial; /* Cancel $irc-line-height */
+        }
+    }
+
     .mx_EventTile {
         --EventTile_irc_line-padding-block: 1px;