You can change the global panel styles by overriding these styles in HeadCSS:

Panel Background:

 

.ui-tooltip-dark .ui-tooltip-content {

    background-color: red;

}

 

Panel Title:

 

.ui-tooltip-dark .ui-tooltip-titlebar {

    color: #FFFFFF;

    font-family: Arial;

    font-size: 22px;

    line-height: 46px;

    text-transform: capitalize;

    background-color: red;