DevTools: [Documentation] fix css style for renderer

Source/devtools/front_end/documentationView.css

 /*
  * Copyright 2014 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.
  */
 
 .documentation-code {
-    border: 1px solid gray;
+    border: 1px solid rgba(128, 128, 128, 0.4);
     border-radius: 6px;
     padding: 10px;
     margin-bottom: 10px;
 }
 
 .documentation-section-title {
     font-size: 120%;
-    padding-bottom: 4px;
     font-weight: bold;
+    padding-top: 5px;
+}
+
+.documentation-section-content.documentation-return-value {
+    margin-top: 10px;
+}
+
+.documentation-parameter-header {
+    margin-top: 10px;
 }
 
 .documentation-link {
     margin-left: 5px;
 }
 
 .documentation-highlighted-text {
     font-weight: bold;
 }
 
 .documentation-view .documentation-method-signature.monospace {
     font-size: 120% !important;
-    border: 1px solid gray;
+    border: 1px solid rgba(128, 128, 128, 0.4);
     border-radius: 6px;
     padding: 10px;
 }
 
 .documentation-section {
     margin-bottom: 15px;
 }
 
 .documentation-section-content {
     margin-left: 16px;
@@ skipping 66 matching lines @@
 }
 
 .documentation-empty-page {
     display: flex;
     flex-direction: column !important;
 }
 
 .documentation-empty-page-align {
     flex-grow: 3;
 }