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;