Fixed hidden-up and hidden-down behavior.

Added zero values for margins, orders, offsets.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "greedo",
-  "version": "1.1.0",
+  "version": "2.0.0",
   "description": "Flexbox-based responsive grid system",
   "main": "greedo.css",
   "style": "greedo.css",

src/css/greedo.scss

@@ -143,6 +143,23 @@ $SIZES: ((-xs, $xs-min), (-sm, $sm-min), (-md, $md-min), (-lg, $lg-min));
 			margin-bottom: calc(1rem * #{$i});
 		}
 	}
+
+	.order#{$size-name}-0 {
+		order: 0;
+	}
+
+	.mt#{$size-name}-0 {
+		margin-top: 0;
+	}
+	.mb#{$size-name}-0 {
+		margin-bottom: 0;
+	}
+
+	.col-offset#{$size-name}-0,
+	.offset#{$size-name}-0 {
+		margin-left: 0;
+		padding: 0 $GUTTER / 2;
+	}
 }
 
 @include generate();
@@ -151,14 +168,14 @@ $SIZES: ((-xs, $xs-min), (-sm, $sm-min), (-md, $md-min), (-lg, $lg-min));
 	@if $size > 0 {
 		@media (min-width: $size) {
 			.hidden#{$size-name},
-			.hidden#{$size-name}-down {
+			.hidden#{$size-name}-up {
 				display: none;
 			}
 			@include generate($size-name);
 		}
 
 		@media (max-width: $size) {
-			.hidden#{$size-name}-up {
+			.hidden#{$size-name}-down {
 				display: none;
 			}
 		}

src/index.html

@@ -379,7 +379,7 @@ <h2>Responsiveness</h2>
 			</div>
 
 			<p>
-				Hidden up example: <code>hidden-[xs,sm,md,lg]-up</code>
+				Hidden down example: <code>hidden-[xs,sm,md,lg]-down</code>
 			</p>
 			<div class="row line">
 				<div class="col-xs-6 col-md-4">
@@ -388,8 +388,8 @@ <h2>Responsiveness</h2>
 				<div class="col-xs-6 col-md-4">
 					<div class="box">.col-xs-6 .col-md-4</div>
 				</div>
-				<div class="col-md-4 hidden-md-up">
-					<div class="box-alt">.col-md-4 .hidden-md-up</div>
+				<div class="col-md-4 hidden-md-down">
+					<div class="box-alt">.col-md-4 .hidden-md-down</div>
 				</div>
 			</div>