jquerymobile.com: Remove unused grade table styles

The page using these styles was removed in 2013 with commit
jquery/jquerymobile.com@392c7ba.

The current browser support pages don't rely on these classes
at https://jquerymobile.com/browser-support/1.3/
and https://jquerymobile.com/browser-support/1.4/

The page has been preserved on the jQuery Mobile Blog, and uses
embedded styles instead.
https://blog.jquerymobile.com/2011/10/19/original-graded-browser-matrix/

Author: Krinkle

themes/jquerymobile.com/style.css

@@ -162,101 +162,3 @@ a, .title, .entry-title { color: #108040; }
 		width: 360px;
 	}
 }
-
-.a, .graded td.a { background: #5fb221; color: #fff; }
-.b, .graded td.b { background: #ff9b0a; color: #fff; }
-.c, .graded td.c { background: #d80700; color: #fff; }
-.f, .graded td.f { background: #333; color: #fff; }
-.next { font-style: italic; }
-.graded td.next { color: rgba(255,255,255,0.6); }
-.cur, .graded td.cur { font-weight: bold; background: #bddcf1; }
-#page .graded td.cur a { font-weight: bold !important; }
-
-.graded {
-	width: 100%;
-	margin: 0 0 30px 0;
-	border-style: collapse;
-	border-spacing: 3px;
-}
-
-#page .graded caption {
-	left: -46px;
-	top: -45px;
-}
-
-#page .graded caption em {
-	padding: 7px 0;
-	text-align: left;
-}
-
-.graded thead th {
-	font-size: 1.4em;
-	width: 30px;
-	padding: 5px 0 5px 0;
-	vertical-align: top;
-	white-space: nowrap;
-}
-
-.graded td {
-	background: #f5f5f5;
-	border-right: solid 1px #fafafa;
-	border-bottom: solid 1px #fafafa;
-	font-size: 1.6em;
-	text-align: center !important;
-	width: 30px;
-	height: 30px;
-	vertical-align: middle;
-}
-
-tr.platform { border-bottom: 5px solid #fff; }
-
-.graded td.platform {
-	padding: 0 5px;
-	white-space: nowrap;
-	font-size: 1.5em;
-	text-align: center;
-	border-right: none;
-	background: #bddcf1;
-	text-shadow: #fff 0 1px 0;
-}
-
-#page .graded td.version a {
-	font-weight: normal;
-}
-
-#page .graded .platform a:hover,
-#page .graded td.version a:hover {
-	text-decoration: underline;
-}
-
-#page .graded td.platform a,
-#page .graded td.cur a {
-	color: #0f212e !important;
-}
-
-.graded td.version {
-	white-space: nowrap;
-	font-size: 1.3em;
-	color: #555;
-	padding: 0 5px;
-}
-.graded thead tr.gr-versions th {
-	font-size: 1.2em;
-	padding: 0 0 5px 0;
-	color: #555;
-}
-
-ul .a, ul .b, ul .c, ul .f, ul .next {
-	padding: 2px 4px;
-}
-
-ul .next {
-	border: solid 1px #ddd;
-	padding: 1px 3px;
-	color: #555;
-}
-
-#graded-support {
-	position: relative;
-	margin-top: 70px;
-}