li { background-color : red }
#t1 { background-color : lime }
li#t2 { background-color : lime }
li#t3 { background-color : lime }
#t4 { background-color : red }

<ul>
  <li id="t1">This list item should have green background because its ID is "t1"</li>
  <li id="t2">This list item should havebe green background because its ID is "t2"</li>
  <li id="t3">
<span id="t44">This list item should have green background because the inner SPAN
                 does not match SPAN#t4</span>
</li>
</ul>