[tools] testbot/web: Make the CollectionBlock <th> cells sticky.

[Francois Gouget]

This keeps the table header visible, making long tables easier to read. 
The header disappears when scrolling past the table so this does not 
impact the remainder of the page.

Signed-off-by: Francois Gouget 
---
 testbot/web/WineTestBot.css | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/testbot/web/WineTestBot.css b/testbot/web/WineTestBot.css
index 3fccbd265..6d170b145 100644
--- a/testbot/web/WineTestBot.css
+++ b/testbot/web/WineTestBot.css
@@ -232,6 +232,8 @@ h2
   padding: 4px;
   margin: 0;
   border: 1px solid white;
+  position: sticky;
+  top: 0;
 }

.CollectionBlock td