Signin screen polish in response to UI review

chrome/browser/resources/chromeos/login/md_header_bar.css

Index: chrome/browser/resources/chromeos/login/md_header_bar.css
diff --git a/chrome/browser/resources/chromeos/login/md_header_bar.css b/chrome/browser/resources/chromeos/login/md_header_bar.css
index 1a49fc5fa86cd1283eee790ddcf6b2672ac3ec23..8e7f58f1b253fd2f6e8f3f9d418e9de23d8104e4 100644
--- a/chrome/browser/resources/chromeos/login/md_header_bar.css
+++ b/chrome/browser/resources/chromeos/login/md_header_bar.css
@@ -60,6 +60,7 @@ html[screen=oobe] .login-header-bar-animate-slow {
 
 .header-bar-item {
   height: 34px;
+  z-index: 3; /* Stays above the scrollable container. */
 }
 
 .add-supervised-user-menu {
@@ -84,9 +85,7 @@ html[screen=oobe] .login-header-bar-animate-slow {
 }
 
 #more-settings-header-bar-item.active button.add-supervised-user-menu:focus {
-  border: 2px solid var(--google-blue-500);
-  border-radius: 2px;
-  padding: 0 15px;
+  font-weight: bold;
 }
 
 html[dir=rtl] .header-bar-item {
@@ -95,6 +94,7 @@ html[dir=rtl] .header-bar-item {
 
 #login-header-bar #shutdown-button-text,
 #login-header-bar #restart-button-text,
+#login-header-bar #show-apps-button-text,
 #login-header-bar #add-user-button-text,
 #login-header-bar #guest-user-button-text,
 #login-header-bar #more-settings-button-text,
@@ -109,6 +109,7 @@ html[dir=rtl] .header-bar-item {
 
 html[dir=rtl] #login-header-bar #shutdown-button-text,
 html[dir=rtl] #login-header-bar #restart-button-text,
+html[dir=rtl] #login-header-bar #show-apps-button-text,
 html[dir=rtl] #login-header-bar #add-user-button-text,
 html[dir=rtl] #login-header-bar #more-settings-button-text,
 html[dir=rtl] #login-header-bar #guest-user-button-text,
@@ -141,6 +142,12 @@ html[dir=rtl] #login-header-bar #unlock-user-button-text {
       url(images/2x/shutdown.svg) 2x );
 }
 
+#login-header-bar #show-apps-button-text {
+  background-image: -webkit-image-set(
+      url(images/1x/show-apps.svg) 1x,
+      url(images/2x/show-apps.svg) 2x );
+}
+
 #login-header-bar #add-user-button-text {
   background-image: -webkit-image-set(
       url(images/1x/add-person.svg) 1x,