gecko/testing/mochitest/tests/SimpleTest/test.css

.test_ok {
	color: green;
	display: none;
}
.test_not_ok {
	color: red;
	display: block;
}

.test_ok, .test_not_ok {
   border-bottom-width: 2px;
   border-bottom-style: solid;
   border-bottom-color: black;
}

.all_pass {
    background-color: lime;
}

.some_fail {
    background-color: red;
}

.tests_report {
	border-width: 2px;
	border-style: solid;
	width: 20em;
       display: table;
}