docs: fix easings example glitch (#9114)

Co-authored-by: Ben McCann <322311+benmccann@users.noreply.github.com>

documentation/examples/11-easing/00-easing/App.svelte

@@ -68,6 +68,10 @@
 </div>
 
 <style>
+	:root {
+		scrollbar-gutter: stable;
+	}
+
 	.easing-vis {
 		display: flex;
 		max-height: 95%;

documentation/examples/11-easing/00-easing/Controls.svelte

@@ -74,18 +74,14 @@
 	ul {
 		list-style: none;
 		padding: 0;
-		display: flex;
-		flex-direction: column;
-		align-items: flex-start;
+		display: grid;
+		grid-template-columns: 1fr;
+		gap: 3px;
 		font-size: 18px;
 	}
 
 	li {
-		padding: 5px 10px;
-		background: #eee;
-		border-radius: 2px;
-		margin: 3px 0;
-		cursor: pointer;
+		display: grid;
 	}
 
 	li:hover {
@@ -93,9 +89,16 @@
 		color: white;
 	}
 
-	.selected {
+	button {
+		border: none;
+		border-radius: 2px;
+		padding: 2px;
+	}
+
+	.selected > button {
 		background: #ff3e00;
 		color: white;
+		font-weight: bold;
 	}
 
 	h3 {