IE compatibility message and W3C standardization

styles/main.css

@@ -30,6 +30,11 @@ a {
     text-align:center;
 }
 
+.IE-header {
+    font-size: 1.5rem;
+    margin: 1rem;
+}
+
 header {
     border-top:.2rem solid #187795;
     box-shadow:0 .4rem .4rem 0 rgba(0,0,0,.04);
@@ -196,7 +201,7 @@ article.main p.signature {
 
 /* Exposition */
 
-article #gallery {
+article .gallery {
     display:inline-block;
     position:relative;
 
@@ -204,23 +209,23 @@ article #gallery {
     margin-top:0;
 }
 
-article.exposition #gallery {
+article.exposition .gallery {
     text-align:center;
 }
 
-article #gallery img {
+article .gallery img {
     max-height:30vh;
     max-width:40vw;
     margin:0.5rem;
 }
 
 @media only screen and (max-width:1000px) {
-    article #gallery img {
+    article .gallery img {
         max-height:85vh;
         max-width:85vw;
     }
 
-    article #gallery {
+    article .gallery {
         display:grid;
         text-align:center;
     }
@@ -351,7 +356,7 @@ article.painting .container .metadata span.content img {
 
 /* Explorer */
 
-article.explorer #gallery {
+article.explorer .gallery {
     text-align:center;
 }
 
@@ -592,7 +597,7 @@ article #stats {
     justify-content:center;
 }
 
-article #stats #stat {
+article #stats .stat {
     width:28vw;
     margin-right:4vw;
     margin-left:4vw;
@@ -603,7 +608,7 @@ article #stats #stat {
         display:block;
     }
 
-    article #stats #stat {
+    article #stats .stat {
         width:85vw;
         text-align:center;
         margin:auto;
@@ -616,7 +621,7 @@ article #stats #stat {
         display:block;
     }
 
-    article #stats #stat {
+    article #stats .stat {
         width:55vw;
         text-align:center;
         margin:auto;