Using CSS :even and :odd pseudo-classes with list items
li { color: blue }
li:nth-child(odd) { color:green }
li:nth-child(even) { color:red }

li:nth-child(even) {
    color:green;
}

li:nth-child(odd) {
    color:red;
}

li { color:blue; }
li:nth-child(odd) { color:green; }
li:nth-child(even) { color:red; }