table#imgtest th,
  table#imgtest td {text-align: center; padding: 5px;}
table#imgtest tbody th {text-align: right;}
table#imgtest img {width: 25px; height: 25px;}

div:empty, span:empty,
li:empty, p:empty,
td:empty, th:empty {padding: 0.5em;
  background: yellow;}

*[style], img, a[href],
  font, center {outline: 5px solid red;}
table, th {border: 5px solid red;}

img[alt][title] {outline-width: 0;}
img[alt] {outline-color: fuchsia;}
img[alt],
  img[title] {outline-style: double;}
img[alt=""][title], img[alt="#"][title],
  img[alt][title=""], img[alt][title="#"] {outline-width: 3px;}
img[alt=""][title=""], img[alt="#"][title="#"] {outline-style: dotted;}

table[summary],
  th[scope="col"],
  th[scope="row"] {border: 1px solid #AAA;}

a[title] {outline-width: 0;}
a[title=""], a[title="#"] {outline-width: 3px;}
a[href="#"] {background: lime;}
a[href=""] {background: fuchsia;}

li {margin: 0.67em 0;}