[css-nesting] adds 2 3 level nest examples

Author: argyleink

css-nesting-1/Overview.bs

@@ -238,6 +238,33 @@ Direct Nesting {#direct}
 		}
 		/* equivalent to
 			 .foo:is(.bar, .foo:is(.baz)) { color: red; }
+		main {
+			display: grid;
+			& > section {
+				background: white;
+				& > header {
+					font-size: 1.25rem;
+				}
+			}
+		}
+		/* equivalent to
+		   main { display: grid; }
+		   main > section { background: white; }
+		   main > section > header { font-size: 1.25rem; }
+		 */
+
+		main {
+			& > section,
+			& > article {
+				background: white;
+				& > header {
+					font-size: 1.25rem;
+				}
+			}
+		}
+		/* equivalent to
+		   main > :is(section, article) { background: white; }
+		   main > :is(section, article) > header { font-size: 1.25rem; }
 		 */
 		</pre>