fix markdown table header CSS

public/css/gogs.css

@@ -1303,7 +1303,7 @@ footer .container .links > *:first-child {
 .markdown table th,
 .markdown table td {
   padding: 6px 13px !important;
-  border: 1px solid #ddd;
+  border: 1px solid #ddd !important;
 }
 .markdown table tr {
   background-color: #fff;

public/less/_markdown.less

@@ -249,8 +249,8 @@
 
 	table th,
 	table td {
-		padding:6px 13px !important;
-		border:1px solid #ddd;
+		padding: 6px 13px !important;
+		border: 1px solid #ddd !important;
 	}
 
 	table tr {