The request a quote button on the top menu shows with white text on a red background when using large screens. When viewed on a mobile screen ie smaller screen the hamburger style menu renders the request a quote button with white text on a white background ie can't be seen. The previous developer (who we are no longer working with) has used custom css. I've included everything here and put in bold what I think is relevant to the problem:

.block-navigation{
display:none;
}

.wpb-js-composer .vc_tta.vc_general.vc_tta-tabs .vc_tta-panel-body  {
  padding: 20px;
}

form.wpcf7-form p:empty,
form.wpcf7-form br {
    display: none;
}

li.rqt_quote_menu{
background-color: #c73333;
  padding:5px !important;
}

li.rqt_quote_menu a{
color: white !important;
}

li.rqt_quote_menu a:hover{
color: #ed6666 !important;
}

.btn-left-center {
  text-align: left;
}

.btn-right-center {
  text-align: right;
}

@media only screen and (max-width: 768px) {
.btn-left-center,
.btn-right-center {
  text-align: center;
  }
}

.block-content {
padding-top:50px;

}

.products .category-overlay {
position: absolute;
bottom: 25% !important;
background-color: #ffffff;
background-color: rgba(255, 255, 255, 0.65) !important;
text-align: center;
padding: 5px !important;
left: 0;
width: 100%;
-o-transition: all 0.3s;
-webkit-transition: all 0.3s;
transition: all 0.3s;
}

.products .category-title
{
font-size: 12px;

}

.gem-prev:after, .gem-next:after{
background: #3399dd !important;

}

body #gform_wrapper_1 .gform_footer input[type=submit]
{
background: #466BA5 !important;
}

body #gform_wrapper_1 .gform_footer input:hover[type=submit]
{
background-color: #2b508a !important;
}

.mailchimp_submit_button{
background-color: #c73333;
border-color: #AA2424;
color: #fff;

Excellent Thanks!