To change the colour of the Green Update box pictured on the right. Add the following CSS overrides:

.btn-success,
.btn-success:active,
.btn-success:focus { /* secondary button */
    color: #000;   
    background: #f0b945;
    border: none;
}

.btn-success:hover {
    color: #fff;   
    background: #f0b945;       
    border: none;
}