Fix a couple of CSS issues.

* remove duplicate property
* fix incompatible property for `background-color`
* remove unit from zero

dist/ratchet-theme-android.css

@@ -467,7 +467,7 @@ textarea,
 }
 
 .backdrop {
-  background-color: none;
+  background-color: transparent;
 }
 
 .popover .bar {

docs/assets/css/docs.css

@@ -400,7 +400,6 @@ body {
 }
 .docs-example-group .example-wrap .example {
   display: block;
-  padding: 4px;
   overflow: hidden;
   padding: 3px;
   width: 100%;
@@ -791,7 +790,7 @@ hr {
   }
 
   .docs-footer .social .twitter-follow-button {
-    margin-top: 0px;
+    margin-top: 0;
   }
 
   .step-title {
@@ -1966,7 +1965,7 @@ hr {
   transform: scale(1);
 }
 .platform-android .backdrop {
-  background-color: none;
+  background-color: transparent;
 }
 .platform-android .popover .bar {
   border-radius: 0;

docs/dist/ratchet-theme-android.css

@@ -467,7 +467,7 @@ textarea,
 }
 
 .backdrop {
-  background-color: none;
+  background-color: transparent;
 }
 
 .popover .bar {

sass/docs.scss

@@ -396,7 +396,6 @@ body {
     }
     .example {
       display: block;
-      padding: 4px;
       overflow: hidden;
       padding: 3px;
       width: 100%;
@@ -803,7 +802,7 @@ hr {
   // Social
   .docs-footer {
     .social .twitter-follow-button {
-      margin-top: 0px;
+      margin-top: 0;
     }
   }
 

sass/theme-android.scss

@@ -623,7 +623,7 @@ textarea,
 
 // Remove the popover's backdrop
 .backdrop {
-  background-color: none;
+  background-color: transparent;
 }
 
 // Popovers with bars