Further remove unneeded elements and styles.

guacamole/src/main/webapp/styles/login.css

@@ -17,6 +17,10 @@
  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+* {
+    -webkit-tap-highlight-color: rgba(0,0,0,0);
+}
+
 body {
     background: #EEE;
     font-family: FreeSans, Helvetica, Arial, sans-serif;