media-player: Dim icon and labels when MPRIS CanRaise is false

When the CanRaise MPRIS property of the connected media player is false, the icon and labels in the media-player details button are dimmed. This is because the button is set to insensitive. The CSS in .media-player-details style class looks like it should fix this, but apparently it does not.

Pasting the CSS below into GTK's interactive debugger fixes this and adds a small highlight to the button when it's not disabled. Actually adding this to common.css file however does nothing. This probably needs the attention of someone who understands CSS selectors better than myself.

/* Highlight details button when it's not disabled */
phosh-media-player .media-player-details {
  background: shade(@phosh_button_bg_color, 1.2);
  opacity: 1.0;
  border-radius: 8px;
  padding-left: 4px;
  -gtk-icon-effect: none;
}
  
phosh-media-player .media-player-details:active {
  background: shade(@phosh_button_bg_color, 1.5);
}

/* The details button should not look inactive even when disabled */
phosh-media-player .media-player-details:disabled {
  background: @phosh_button_bg_color;
}