a11y OOBE: Improve version number text

See bug for the screenshot

Bug: 881471
Change-Id: I5b996648fe423799ba67450fe8f5996adbf70520
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1818527Reviewed-by: Denis Kuznetsov <antrim@chromium.org>
Commit-Queue: Roman Sorokin [CET] <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#700200}

ui/login/oobe.css

@@ -7,6 +7,7 @@
  */
 
 :root {
+  --google-grey-700: rgb(95, 99, 104);
   --shelf-area-height: 57px;
 }
 
@@ -151,15 +152,11 @@ span.bold {
 }
 
 #version-labels {
-  color: #fff;
-  font-size: 11px;
+  color: var(--google-grey-700);
+  font-size: 13px;
   margin: 10px;
   position: relative;
   text-align: end;
-  text-shadow:
-      0 0 4px rgba(0,0,0,.6),
-      0 1px 2px rgba(0,0,0,.8),
-      0 -1px 2px rgba(0,0,0,1);
   transition: all 500ms linear;
   z-index: 1;
 }