Placeholder color can be set using shorthand class .ph-{color}
.ph-{color}
Class: .ph-indigo-light
.ph-indigo-light
<input type="text" class="...border-indigo ph-indigo-light" placeholder="First Name" />
Class: .focus-ph-indigo-light
.focus-ph-indigo-light
<input type="text" class="...ph-gray-light focus-ph-indigo-light" placeholder="First Name" />