Fix express button display in the Cart block (#10534)

* Fix express button display in the Cart block

When multiple buttons are displayed they don't appear stacked. This PR fixes a regression;

* Fix editor experience

assets/js/blocks/cart-checkout-shared/payment-methods/express-payment/style.scss

@@ -5,18 +5,13 @@ $border-radius: 5px;
 	margin: auto;
 	position: relative;
 
+	// nested class to avoid conflict with .editor-styles-wrapper ul
 	.wc-block-components-express-payment__event-buttons {
-		list-style: none;
-		display: grid;
-		grid-template-columns: repeat(auto-fit, minmax(calc(33% - 10px), 1fr));
-		grid-gap: 10px;
-		box-sizing: border-box;
 		width: 100%;
 		padding: 0;
 		margin: 0;
 		overflow: hidden;
 		text-align: center;
-
 		> li {
 			margin: 0;
 			width: 100%;
@@ -27,18 +22,23 @@ $border-radius: 5px;
 			}
 		}
 	}
-
-	@include breakpoint("<782px") {
-		.wc-block-components-express-payment__event-buttons {
-			grid-template-columns: 1fr;
-		}
-	}
 }
 
 .wc-block-components-express-payment--checkout {
 	/* stylelint-disable-next-line function-calc-no-unspaced-operator */
 	margin-top: calc($border-radius * 3);
 
+	.wc-block-components-express-payment__event-buttons {
+		list-style: none;
+		display: grid;
+		grid-template-columns: repeat(auto-fit, minmax(calc(33% - 10px), 1fr));
+		grid-gap: 10px;
+
+		@include breakpoint("<782px") {
+			grid-template-columns: 1fr;
+		}
+	}
+
 	.wc-block-components-express-payment__title-container {
 		display: flex;
 		flex-direction: row;