<!DOCTYPE html> <!-- webkit-test-runner [ LayoutFormattingContextEnabled=true LayoutFormattingContextIntegrationEnabled=false ] -->
<style>
table {
border: 10px solid green;
}
th {
width: 20px;
height: 20px;
thead {
border: 50px solid red;
</style>
<table>
<thead>
<tr><th></th><th></th></tr>
</thead>
</table>