Mobile: Hamburger and back btn: Fix height after table to div

With "Change table layout to CSS base table structure" and "Adjust
table elements for mobile view." changes we now have more divs instead
of table elements but with that the hamburger menu is now mislaigned
   - Fix height
   - To do: ideally we would make both hamburger menu and the button
   at its side rendered with the exact same structure which is not the
   case. And ultimately remove height and just have it flex stretch etc

Signed-off-by: Pedro Pinto Silva <pedro.silva@collabora.com>
Change-Id: Id9365df82f1caff132dde41760a06689ec1145d1

browser/css/device-mobile.css

@@ -15,7 +15,7 @@ html[dir='rtl'] .sub-menu-arrow {
 /* Related to cool.css */
 #toolbar-hamburger {
 	width: 36px;
-	height: 36px;
+	height: 42px;
 	position: relative;
 	z-index: 1002;
 	display: flex;
@@ -37,8 +37,7 @@ html[dir='rtl'] .sub-menu-arrow {
 
 /* Related to back button */
 #toolbar-mobile-back {
-	width: 36px;
-	height: 36px;
+	width: 42px;
 	position: relative;
 	z-index: 1003;
 }