Index: src/wp-content/themes/twentytwenty/style.css
===================================================================
--- src/wp-content/themes/twentytwenty/style.css	(revision 47591)
+++ src/wp-content/themes/twentytwenty/style.css	(working copy)
@@ -1871,13 +1871,23 @@
 	flex-shrink: 0;
 }
 
+@media (max-width: 700px) {
 
+	.menu-wrapper {
+		width: 100%;
+	}
+
+	button.close-nav-toggle {
+		width: calc(100% - 2rem);
+	}
+}
+
 /* Main Menu --------------------------------- */
 
 .modal-menu {
 	position: relative;
-	left: calc(50% - 50vw);
-	width: 100vw;
+	left: auto;
+	width: 100%;
 }
 
 .modal-menu li {
@@ -1947,6 +1957,7 @@
 
 .modal-menu ul li {
 	border-left-width: 1rem;
+	border-left-color: transparent;
 }
 
 .modal-menu ul li a {
@@ -4923,11 +4934,6 @@
 		margin-right: 2.1rem;
 	}
 
-	.modal-menu {
-		left: auto;
-		width: 100%;
-	}
-
 	.modal-menu > li > a,
 	.modal-menu > li > .ancestor-wrapper > a {
 		font-size: 2.4rem;
@@ -4934,10 +4940,6 @@
 		padding: 2.5rem 0;
 	}
 
-	.modal-menu ul li {
-		border-left-color: transparent;
-	}
-
 	.modal-menu > li > .ancestor-wrapper > button.sub-menu-toggle {
 		padding: 0 3rem;
 	}