/* basic positioning */
.legend {
  list-style: none;
}
.legend li {
  margin-right: 10px;
}
.legend span {
  border: 1px solid #ccc; float: left; width: 12px; height: 12px; margin: 2px;
}
/* your colors */
.legend .noCases { background-color: #DDD; }
.legend .over0 { background-color: #FFFFD4; }
.legend .over10 { background-color: #FEE391; }
.legend .over25 { background-color: #FEC44F; }
.legend .over50 { background-color: #FE9929; }
.legend .over100 { background-color: #D95F0E; }
.legend .over125 { background-color: #993404; }