Polybar: Switch brightness indicator to Material

.config/polybar/config

@@ -93,7 +93,7 @@ border-top-color = ${res/colors.background-2}
 
 modules-left = i3 bspwm | wlan-network eth-network | mpd
 modules-center = xwindow-label
-modules-right = temperature-label cpu-label memory-label | xbacklight-label volume-ramp battery-ramp | date
+modules-right = temperature-label cpu-label memory-label | xbacklight-ramp volume-ramp battery-ramp | date
 
 ;========================================
 ; MODULES
@@ -442,15 +442,22 @@ label-connected =  %upspeed%  %downspeed%
 label-connected-foreground = ${res/colors.primary-dark}
 label-disconnected = 
 
-[module/xbacklight-label]
+[module/xbacklight-ramp]
 type = internal/xbacklight
-format = <label>
+format = <ramp> <label>
 format-underline = ${res/colors.underline-backlight}
-format-prefix = " "
-format-prefix-foreground = ${self.format-underline}
 
 label = %percentage%%
 
+ramp-0 = 
+ramp-1 = 
+ramp-2 = 
+ramp-3 = 
+ramp-4 = 
+ramp-5 = 
+ramp-6 = 
+ramp-foreground = ${self.format-underline}
+
 [module/xkeyboard-label]
 type = internal/xkeyboard
 format = <label-indicator>