update margin of #p-search

Signed-off-by: WaitSpring <me@waitspring.com>

resources/screen-mobile.less

@@ -54,7 +54,7 @@
 
 #p-search {
 	.flex(1, 1, 100%, 4);
-	margin: 0.25em 1em;
+	margin: 0.125em auto;
 
 	.sidebar-inner {
 		left: 0;