MD Downloads: update page margins/layout

chrome/browser/resources/md_downloads/item.css

 /* Copyright 2015 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file. */
 
 :host {
   @apply(--downloads-shared-style);
   display: flex;
-  margin: 32px 0;
+  margin: 24px 0;
 }
 
 :host([hide-date]) {
-  margin-top: -16px;
+  margin-top: -12px;
+}
+
+:host(:not(:first-of-type):not([hide-date])) {
+  border-top: 1px solid rgba(0, 0, 0, .14);
+  padding-top: 30px;
+}
+
+:host(:first-of-type),
+:host(:not(:first-of-type):not([hide-date])) {
+  margin-top: 30px;
 }
 
 #date-container,
 #end-cap {
   flex: 1 0 var(--downloads-side-column-basis);
 }
 
 #date-container > * {
-  color: #616161;
-  font-size: 107.69%;
+  color: #5a5a5a;
+  font-size: 92.3%;
   font-weight: bold;
 }
 
 :host([hide-date]) #date-container {
   visibility: hidden;
 }
 
 #content {
   background: white;
   border-radius: 2px;  /* TODO(dbeam): why does this differ from Polymer? */
@@ skipping 121 matching lines @@
 #remove {
   --paper-icon-button: {
     height: 16px;
     width: 16px;
   };
   --iron-icon-height: 16px;
   --iron-icon-width: 16px;
 }
 
 @media not all and (max-width: 1024px) {
-  /* Only show date separators in wide mode. */
-  :host(:not(:first-of-type):not([hide-date])) :-webkit-any(#content-wrapper,
-                                                            #since) {
-    border-top: 1px solid rgba(0, 0, 0, .2);  /* TODO(dbeam): real color. */
-    padding-top: 32px;
-  }
-
   #date-container > * {
     -webkit-margin-start: 24px;
   }
 }
 
 @media all and (max-width: 1024px) {
   /* In narrow windows, put the dates on top instead of on the side. */
   :host {
     flex-direction: column;
   }
 
   :host([hide-date]) #date-container,
   #end-cap {
     display: none;
   }
 
   #content {
     margin: 0 auto;
   }
 
   #date-container {
     flex: none !important;
-    margin: 0 auto 32px;
+    margin: 0 auto 30px;
     width: var(--downloads-item-width);
   }
 }