[CSS] Fix `pre` element overflow

`overflow-x` property is affected by parent node width.

Change-Id: I77f8aae16606db9f0429b9f279d0811fe47abc1b

gitiles-servlet/src/main/resources/com/google/gitiles/static/base.css

diff --git a/gitiles-servlet/src/main/resources/com/google/gitiles/static/base.css b/gitiles-servlet/src/main/resources/com/google/gitiles/static/base.css
index e7505e8..2a56084 100644
--- a/gitiles-servlet/src/main/resources/com/google/gitiles/static/base.css
+++ b/gitiles-servlet/src/main/resources/com/google/gitiles/static/base.css
@@ -275,6 +275,7 @@
 .RepoShortlog-log {
   -ms-flex: 1;
   flex: 1;
+  width: 80%;
 }
 .RepoIndexDoc {
   border-top: 1px solid #ddd;