Split Zuul Summary and Change log, improve visibility in dark mode

When using the dark theme even job entry color is the same as Change Log
While there is a visible shadow with the bright theme, this shadow is
not visible with the dark theme.
This patch adds a small padding to make sure a primary background color
zone is present before Change Log
diff --git a/zuul-results-summary/zuul-results-summary.js b/zuul-results-summary/zuul-results-summary.js
index 0e3c16d..48e68fd 100644
--- a/zuul-results-summary/zuul-results-summary.js
+++ b/zuul-results-summary/zuul-results-summary.js
@@ -73,7 +73,7 @@
   </style>
 
   <template is="dom-repeat" items="[[__table]]">
-   <div style="padding-left:5px">
+   <div style="padding-left:5px; padding-bottom:2px;">
    <table>
     <tr>
      <th>