better selectors, eliminate unnecessary CSS

less/general.less

@@ -9,14 +9,10 @@ body, textarea {
 }
 
 @media (max-width:870px) {
-	.row [class*='c']{
+	.row column {
 		width: 100%;
-		display: block;
 		margin: 1% auto;
 	}
-	.row:last-child column {
-		margin-bottom: 2.5em;
-	}
 }
 
 .container {