proxadmin/app/static/css/panel-transparent.css

.panel-transparent {
    background: none;
}
  
.panel-transparent .panel-heading {
    background: rgb(255, 255, 255); /* fallback */
    background: rgba(255, 255, 255, 0.6)!important;
}

.panel-transparent .panel-body{
    background: rgb(255, 255, 255); /* fallback */
    background: rgba(255, 255, 255, 0.5)!important;
}