Restyle main layout

app/src/frontend/styles/layout.css

@@ -1,20 +1,34 @@
 /**
  * Main Layout
  */
- main {
+
+html, body, #root {
+    height: 100%;
+}
+
+body {
+    margin: 0;
+}
+
+#root {
+    display: flex;
+    flex-direction: column;
+    overflow: hidden;
+}
+
+main {
     position: relative;
-    min-height: 35rem;
+    flex: 1;
+    display: flex;
+    flex-direction: column;
+    overflow: hidden;
 }
-@media (min-width: 768px){
+
+@media(min-width: 768px) {
     main {
-        position: absolute;
+        flex-direction: row;
-        top: 79px; /* matches 79px .main-header */
-        bottom: 0;
-        left: 0;
-        right: 0;
-        min-height: auto;
     }
-}
+ }
 /**
  * Text pages
  */