Supervised user interstitial: Small style changes.

chrome/browser/resources/supervised_user_block_interstitial.css

Index: chrome/browser/resources/supervised_user_block_interstitial.css
diff --git a/chrome/browser/resources/supervised_user_block_interstitial.css b/chrome/browser/resources/supervised_user_block_interstitial.css
index 73371284a6cf82982089c812567047ce6e308948..86ff2afd4b36ad7780249d6f0697e81aaa86e924 100644
--- a/chrome/browser/resources/supervised_user_block_interstitial.css
+++ b/chrome/browser/resources/supervised_user_block_interstitial.css
@@ -28,7 +28,7 @@ h1 {
   color: rgb(102, 102, 102);
   font-size: 1.3em;
   font-weight: normal;
-  margin: 5px 0 30px 0;
+  margin: 5px 0 25px 0;
 }
 
 a {
@@ -75,22 +75,11 @@ button {
   box-shadow: inset 0 1px 0 rgb(255, 255, 255);
   color: rgb(102, 102, 102);
   font-weight: bold;
-  margin: 5px 0;
+  margin: 5px 3px;
   padding: 8px 13px;
   text-shadow: 0 1px 0 rgba(255, 255, 255, 0.8);
 }
 
-#back-button {
-  background-image: linear-gradient(rgb(84, 153, 244) 5%,
-                                    rgb(82, 148, 242) 50%,
-                                    rgb(75, 133, 241));
-  border: 1px solid rgb(81, 135, 223);
-  border-bottom: 1px solid rgb(56, 112, 207);
-  box-shadow: inset 0 1px 0 rgb(95, 168, 247);
-  color: rgb(255, 255, 255);
-  text-shadow: 0 1px 0 rgba(0, 0, 0, 0.2);
-}
-
 @media (min-width: 376px) {
   #back-button {
     width: 100px;