MAPG-89 unify styles

public/static/css/mapguesser.css

@@ -17,6 +17,11 @@ button::-moz-focus-inner, input::-moz-focus-inner {
     border: 0;
 }
 
+/* to be compatible with browsers that don't know <main> */
+main {
+    display: block;
+}
+
 ::selection {
     background-color: #28a745;
     color: #ffffff;
@@ -324,10 +329,11 @@ main {
     padding: 6px 12px;
 }
 
-div.full {
+main.full {
     position: relative;
     width: 100%;
     height: calc(100% - 40px);
+    padding: 0;
 }
 
 footer {