changes

- bump to v1.0.0-alpha.23
- fix header layout within drawer demos
- fix drawer layout within drawer layout issues
- upgrade drawer layout to flexbox

Author: lazabogdan

demo/src/html/pages/header-layout-drawer-transform-fx.html

@@ -15,11 +15,6 @@
 
     /* Drawer */
     .mdk-drawer__content {
-      position: absolute;
-      top: 0;
-      left: 0;
-      right: 0;
-      bottom: 0;
       width: 290px;
     }
     .mdk-drawer__inner > :first-child {

demo/src/html/pages/header-layout-drawer.html

@@ -15,11 +15,6 @@
 
     /* Drawer */
     .mdk-drawer__content {
-      position: absolute;
-      top: 0;
-      left: 0;
-      right: 0;
-      bottom: 0;
       width: 290px;
     }
     .mdk-drawer__inner > :first-child {