Fix font size in tfoot section in code coverage report.

TBR=mmoroz@chromium.org

Change-Id: Ic835553e8955ca3618a6c0b3a4187d4e5f94ddfe
Reviewed-on: https://chromium-review.googlesource.com/1051034Reviewed-by: Abhishek Arya <inferno@chromium.org>
Reviewed-by: Max Moroz <mmoroz@chromium.org>
Commit-Queue: Abhishek Arya <inferno@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557064}

tools/code_coverage/html_templates/style_overrides.css

@@ -6,16 +6,19 @@ th, td {
   padding: 5px 16px;
 }
 
-tbody td {
+tbody td, tfoot td {
   font-size: 14px;
 }
 
+thead th {
+  font-size: 16px;
+}
+
 thead th, tfoot td {
   background-color: #f5f5f5;
   border-left: 1px solid #e4e4e4;
   border-right: 1px solid #e4e4e4;
   color: #484848;
-  font-size: 16px;
   text-transform: uppercase;
 }