guacamole/src/main/webapp/app/form/templates/guacInputColor.html

<div class="guac-input-color"
     ng-class="{
         'dark' : isDark(),
         'read-only' : colorPickerUnavailable
     }"
     ng-style="{
        'background-color' : model
     }">
    <ng-transclude></ng-transclude>
</div>