last minor UI fixes

index.html

@@ -105,7 +105,12 @@
                 padding-top: 1.2rem;
                 padding-bottom: 1.2rem;
                 font-size:80%;
-                max-width:1077pt;
+                /*
+                    site data containers      :  3 ×   30rem
+                  + padding between them      :  2 ×    2rem
+                  + menu buttons outer margin :  2 × 0.25rem
+                */
+                max-width:94.5rem;
                 margin:auto;
             }
             #internal-main-menu-container {
@@ -115,11 +120,11 @@
             }
             #internal-main-menu-container p {
                 font-size: 100%;
-                margin: 0.3em 0.2em;
+                margin: 0.15rem 0.25rem;
                 padding: 0.5em 1em 0.5em 0.2em;
             }
             #internal-main-menu-container input[type=button] {
-                margin: 0.3em;
+                margin: 0.25rem;
                 flex-grow:1;
                 flex-shrink:1;
                 padding-left:0.5em;
@@ -242,7 +247,7 @@
                 border: dotted 1px springgreen;
                 line-height: 90%;
                 outline:none;
-                text-align: Center;
+                text-align:center;
                 color: springgreen;
                 display: none;
                 cursor: pointer;