fix #3

_sass/minima/_base.scss

@@ -170,18 +170,18 @@ pre {
 
 
 .main {
-  max-width: -webkit-calc(#{$content-width} - (#{$spacing-unit} * 2));
-  max-width:         calc(#{$content-width} - (#{$spacing-unit} * 2));
+  max-width: $content-width;
   margin-right: auto;
   margin-left: auto;
   height: 100%;
   @extend %clearfix;
   position: relative;
   background-color: $background-color;
+  box-shadow: 0 10px 20px 0 #999999;
 
   @include media-query($on-laptop) {
-    max-width: -webkit-calc(#{$content-width} - (#{$spacing-unit}));
-    max-width:         calc(#{$content-width} - (#{$spacing-unit}));
+    max-width: $content-width;
+    max-width: $content-width;
     padding-right: $spacing-unit / 2;
     padding-left: $spacing-unit / 2;
   }