chromium/src/third_party/blink/perf_tests/layout/resources/large-table-with-collapsed-borders.css

html, body {
    margin: 0;
}

table {
    border-collapse: collapse;
    border : 1px solid red;
}
td {
    border : 1px solid blue;
    width: 5px;
    height: 5px;
}