Index: wp-admin/js/theme.js
===================================================================
--- wp-admin/js/theme.js	(revision 27620)
+++ wp-admin/js/theme.js	(working copy)
@@ -1153,11 +1153,14 @@
 	searchContainer: $( '.theme-navigation' ),
 
 	uploader: function() {
-		$( 'a.upload.button' ).on( 'click', function() {
-			$( '.upload-theme' )
-				.toggleClass( 'opened' )
-				.hasClass( 'opened' ) ? $( this ).text( l10n.back ) : $( this ).text( l10n.upload );
+		$( 'a.upload' ).on( 'click', function() {
+			$( 'body' ).addClass( 'show-upload-theme' );
+			themes.router.navigate( themes.router.baseUrl( '?upload' ), { replace: true } );
 		});
+		$( 'a.browse-themes' ).on( 'click', function() {
+			$( 'body' ).removeClass( 'show-upload-theme' );
+			themes.router.navigate( themes.router.baseUrl( '' ), { replace: true } );
+		});
 	},
 
 	moreFilters: function() {
@@ -1168,7 +1171,8 @@
 themes.InstallerRouter = Backbone.Router.extend({
 	routes: {
 		'theme-install.php?theme=:slug': 'preview',
-		'theme-install.php(?sort=:sort)': 'sort',
+		'theme-install.php?sort=:sort': 'sort',
+		'theme-install.php?upload': 'upload',
 		'': 'sort'
 	},
 
@@ -1225,6 +1229,10 @@
 			self.view.trigger( 'theme:close' );
 		});
 
+		themes.router.on( 'route:upload', function( slug ) {
+			$( 'a.upload' ).trigger( 'click' );
+		});
+
 		this.extraRoutes();
 	},
 
Index: wp-admin/css/themes.css
===================================================================
--- wp-admin/css/themes.css	(revision 27620)
+++ wp-admin/css/themes.css	(working copy)
@@ -1065,9 +1065,6 @@
   16.2 - Install Themes
 ------------------------------------------------------------------------------*/
 
-.theme-install-php h2 .upload {
-	margin-left: 10px;
-}
 .theme-navigation {
 	background: #fff;
 	box-shadow: 0 1px 1px 0 rgba(0,0,0,.1);
@@ -1081,6 +1078,17 @@
 	position: relative;
 	width: 100%;
 }
+.theme-install-php a.upload,
+.theme-install-php a.browse-themes {
+	cursor: pointer;
+}
+.theme-install-php a.browse-themes,
+.theme-install-php.show-upload-theme a.upload {
+	display: none;
+}
+.theme-install-php.show-upload-theme a.browse-themes {
+	display: inline;
+}
 .upload-theme {
 	-moz-box-sizing: border-box;
 	box-sizing: border-box;
@@ -1092,7 +1100,7 @@
 	position: relative;
 		top: 10px;
 }
-.upload-theme.opened {
+body.show-upload-theme .upload-theme {
 	display: block;
 }
 .upload-theme .wp-upload-form {
@@ -1110,8 +1118,8 @@
 	padding: 40px 0 0;
 	text-align: center;
 }
-.upload-theme.opened + .theme-navigation,
-.upload-theme.opened + .theme-navigation + .theme-browser {
+body.show-upload-theme .upload-theme + .theme-navigation,
+body.show-upload-theme .upload-theme + .theme-navigation + .theme-browser {
 	display: none;
 }
 .theme-navigation .theme-count {
@@ -1201,6 +1209,26 @@
 	display: none !important;
 }
 
+@media only screen and (max-width: 1120px) {
+	.theme-install-php .theme-search {
+		margin: 20px 0;
+		position: static;
+		width: 100%;
+	}
+	.more-filters-container {
+		border-bottom: 1px solid #eee;
+	}
+	.upload-theme .wp-upload-form {
+		margin: 20px 0;
+		max-width: 100%;
+	}
+	.upload-theme .install-help {
+		font-size: 15px;
+		padding: 20px 0 0;
+		text-align: left;
+	}
+}
+
 .rating {
 	margin: 30px 0;
 }
Index: wp-admin/theme-install.php
===================================================================
--- wp-admin/theme-install.php	(revision 27620)
+++ wp-admin/theme-install.php	(working copy)
@@ -104,7 +104,8 @@
 <div class="wrap">
 	<h2>
 		<?php echo esc_html( $title ); ?>
-		<a class="upload button button-secondary"><?php esc_html_e( 'Upload Theme' ); ?></a>
+		<a class="upload add-new-h2"><?php esc_html_e( 'Upload Theme' ); ?></a>
+		<a class="browse-themes add-new-h2"><?php esc_html_e( 'Browse' ); ?></a>
 	</h2>
 
 	<div class="upload-theme">