:root { --whatsapp-green: #25D366; --whatsapp-dark: #128C7E; }
html, body { height: 100%; }
.form-control:focus { border-color: var(--whatsapp-green); box-shadow: 0 0 0 .2rem rgba(37,211,102,.25); }
.btn-primary { background: var(--whatsapp-green); border-color: var(--whatsapp-green); }
.btn-primary:hover { background: var(--whatsapp-dark); border-color: var(--whatsapp-dark); }