Wie wäre es damit: https://addons.mozilla.org/de/firefox/add…tom-scrollbars/ ?
Oder du versuchst mal folgendes Skript:
// Farbige, abgerundete Scrollbalken mit Buttons :)
"use strict";
/* Firefox 57+ userChrome.js tweaks - SCROLLBARS ********************************************** */
/* by Aris (aris-addons@gmx.net)*************************************************************** */
/* Github: https://github.com/Aris-t2/CustomJSforFx/blob/master/scripts/custom_scrollbars.uc.js */
/* ******************************************************************************************** */
/* ******************************************************************************************** */
/* Custom Scrollbars for Firefox ************************************************************** */
/* version 1.0.4 ****************************************************************************** */
/* ******************************************************************************************** */
/* ***********************************************************************************************
README
ENABLING options > set var to true
DISABLING options > set var to false
Modifying appearance > change values
- color - name: red, blue, transparent / hex code: #33CCFF, #FFF
- color - rgb(a): rgba(0,0,255,0.8) / hsl(a): hsla(240,100%,50%,0.8)
- numbers: 1, 2, 3 ... 10, 11, 12 ...
- opacity: 0.0 to 1.0 e.g. 1.4, 1,75
- gradients: linear-gradient(direction, color, color, color)
- gradients example: linear-gradient(to right, blue, #33CCFF, rgba(0,0,255,0.8))
- unsettings predefined gradients: transparent,rgba(255,255,255,0.5),transparent -> transparent,rgba(255,255,255,0.0),transparent
- button size with arrow (descriptions for vertical scrollbars - analogous for horizontal scrollbars)
-- 1: space above arrow = arrow height
-- 1.5: space above arrow = 0.5 * arrow height
-- 2: no space above arrow
NOTE
- This is a tiny collection of scrollbar tweaks, not a port of 'NewScrollbars' add-on!
- Small scrollbar width values will corrupt some parts of the ui!
*********************************************************************************************** */
// GENERAL SCROLLBAR SETTINGS
var hide_scrollbars = false; // default: hide_scrollbars = false
var hide_scrollbar_buttons = false; // default: hide_scrollbar_buttons = false
var custom_scrollbar_size = true; // default: custom_scrollbar_size = false
var custom_scrollbar_size_value = 17; // in px // default: custom_scrollbar_size_value = 17
var custom_scrollbar_opacity = false; // default: custom_scrollbar_opacity = false
var custom_opacity_value = "1.0"; // default: custom_opacity_value = "1.0"
// floating scrollbars
var enable_scrollbars_on_top_of_webcontent = false; // default: enable_scrollbars_on_top_of_webcontent = false // uses 'custom_scrollbar_size_value' inside its code
// custom scrollbars
var enable_custom_scrollbars = true; // default: enable_custom_scrollbars = true
// CUSTOM SCROLLBAR SETTINGS ("custom_scrollbar_" --> "cs_")
var cs_thumb_border = 1; // in px // default: cs_thumb_border = 0
var cs_thumb_roundness = 5; // in px // default: cs_thumb_roundness = 0
var cs_buttons_roundness = 0; // in px // default: cs_buttons_roundness = 0
var cs_buttons_as_arrows = false; // default: cs_buttons_as_arrows = false // uses 'custom_scrollbar_size_value' inside its code
var cs_arrows_on_buttons = true; // default: cs_arrows_on_buttons = true // uses 'custom_scrollbar_size_value' inside its code
// button size with arrow - 1: space above arrow = arrow height // 1.5: space above arrow = 0.5 * arrow height // 2: no space above arrow
var cs_arrows_on_buttons_buttons_size = 1.5; // default: cs_arrows_on_buttons_buttons_size = 1.5
// 'flat' scrollbars
var cs_ignore_color_gradients = true; // default: cs_ignore_color_gradients = false
// CUSTOM SCROLLBAR COLORS/GRADIENTS
// - background
var cs_background_color = "#171717"; // default: cs_background_color = "#DDDDDD"
//var cs_background_image_vertical = "linear-gradient(to right,transparent,rgba(255,255,255,0.5),transparent)"; // default: cs_background_image_vertical = "unset"
var cs_background_image_vertical = "unset"; // default: cs_background_image_vertical = "unset"
//var cs_background_image_horizontal = "linear-gradient(to bottom,transparent,rgba(255,255,255,0.5),transparent)"; // default: cs_background_image_horizontal = "unset"
var cs_background_image_horizontal = "unset"; // default: cs_background_image_horizontal = "unset"
// - corner
var cs_corner_background_color = "#DDDDDD"; // default: cs_corner_background_color = "#DDDDDD"
var cs_corner_background_image = "linear-gradient(45deg,transparent 30%,rgba(255,255,255,0.5) 50%,transparent 70%),linear-gradient(-45deg,transparent 30%,rgba(255,255,255,0.5) 50%,transparent 70%)"; // default: cs_corner_background_image = "unset"
// - thumb/slider
var cs_thumb_color = "rgb(80,80,80)"; // default: cs_thumb_color = "#33CCFF"
var cs_thumb_image_vertical = "linear-gradient(to right,transparent,rgba(255,255,255,0.5),transparent)"; // default: cs_thumb_image_vertical = "unset"
var cs_thumb_image_horizontal = "linear-gradient(to bottom,transparent,rgba(255,255,255,0.5),transparent)"; // default: cs_thumb_image_horizontal = "unset"
var cs_thumb_hover_color = "rgb(50,50,52"; // default: cs_thumb_hover_color = "#66FFFF"
var cs_thumb_hover_image_vertical = "linear-gradient(to right,transparent,rgba(255,255,255,0.5),transparent)"; // default: cs_thumb_hover_image_vertical = "unset"
var cs_thumb_hover_image_horizontal = "linear-gradient(to bottom,transparent,rgba(255,255,255,0.5),transparent)"; // default: cs_thumb_hover_image_horizontal = "unset"
var cs_thumb_border_color = "rgb(0,200,0)"; // default: cs_thumb_border_color = "#33CCFF"
// - buttons
var cs_buttons_color = "rgb(0,200,0)"; // default: cs_buttons_color = "#66FFFF"
var cs_buttons_image_vertical = "linear-gradient(to right,transparent,rgba(255,255,255,0.5),transparent)"; // default: cs_buttons_image_vertical = "unset"
var cs_buttons_image_horizontal = "linear-gradient(to bottom,transparent,rgba(255,255,255,0.5),transparent)"; // default: cs_buttons_image_horizontal = "unset"
var cs_buttons_hover_color = "green"; // default: cs_buttons_hover_color = "#33CCFF"
var cs_buttons_hover_image_vertical = "linear-gradient(to right,transparent,rgba(255,255,255,0.5),transparent)"; // default: cs_buttons_hover_image_vertical = "unset"
var cs_buttons_hover_image_horizontal = "linear-gradient(to bottom,transparent,rgba(255,255,255,0.5),transparent)"; // default: cs_buttons_hover_image_horizontal = "unset"
// - button arrows
var cs_arrows_on_buttons_color = "green"; // default: cs_arrows_on_buttons_color = "#33CCFF"
var cs_arrows_on_buttons_hover_color = "red"; // default: cs_arrows_on_buttons_hover_color = "#66FFFF"
// unset background image color gradients -> flat scrollbars
if(cs_ignore_color_gradients==true)
cs_background_image_vertical
=cs_background_image_horizontal
=cs_corner_background_image=cs_thumb_image_vertical
=cs_thumb_image_horizontal
=cs_thumb_hover_image_vertical
=cs_thumb_hover_image_horizontal
=cs_buttons_image_vertical
=cs_buttons_image_horizontal
=cs_buttons_hover_image_vertical
=cs_buttons_hover_image_horizontal
="unset";
/* ******************************************************************************************** */
/* ******************************************************************************************** */
/* ******************************************************************************************** */
// Scrollbar code
Components.utils.import("resource://gre/modules/Services.jsm");
var ss = Components.classes["@mozilla.org/content/style-sheet-service;1"].getService(Components.interfaces.nsIStyleSheetService);
var custom_scrollbars = {
init: function() {
var uri = Services.io.newURI("data:text/css;charset=utf-8," + encodeURIComponent('\
\
@namespace html url("http://www.w3.org/1999/xhtml");\
\
scrollbar, scrollcorner, scrollbar thumb, scrollbar scrollbarbutton {\
-moz-appearance: none !important;\
}\
scrollbar {\
background-color: '+cs_background_color+' !important;\
}\
scrollbar[orient="vertical"] {\
background-image: '+cs_background_image_vertical+' !important;\
}\
scrollbar[orient="horizontal"] {\
background-image: '+cs_background_image_horizontal+' !important;\
}\
scrollcorner {\
background-color: '+cs_corner_background_color+' !important;\
background-image: '+cs_corner_background_image+' !important;\
}\
scrollbar thumb {\
background-color: '+cs_thumb_color+' !important;\
border-radius: '+cs_thumb_roundness+'px !important;\
border: '+cs_thumb_border+'px solid '+cs_thumb_border_color+' !important;\
}\
scrollbar thumb[orient="vertical"] {\
background-image: '+cs_thumb_image_vertical+' !important;\
}\
scrollbar thumb[orient="horizontal"] {\
background-image: '+cs_thumb_image_horizontal+' !important;\
}\
scrollbar thumb:hover, scrollbar thumb:active {\
background-color: '+cs_thumb_hover_color+' !important;\
}\
scrollbar thumb[orient="vertical"]:hover, scrollbar thumb[orient="vertical"]:active {\
background-image: '+cs_thumb_hover_image_vertical+' !important;\
}\
scrollbar thumb[orient="horizontal"]:hover, scrollbar thumb[orient="horizontal"]:active {\
background-image: '+cs_thumb_hover_image_horizontal+' !important;\
}\
scrollbar scrollbarbutton {\
background-color: '+cs_buttons_color+' !important;\
border-radius: '+cs_buttons_roundness+'px !important;\
}\
scrollbar[orient="vertical"] scrollbarbutton {\
background-image: '+cs_buttons_image_vertical+' !important;\
}\
scrollbar[orient="horizontal"] scrollbarbutton {\
background-image: '+cs_buttons_image_horizontal+' !important;\
}\
scrollbar scrollbarbutton:hover {\
background-color: '+cs_buttons_hover_color+' !important;\
}\
scrollbar[orient="vertical"] scrollbarbutton:hover {\
background-image: '+cs_buttons_hover_image_vertical+' !important;\
}\
scrollbar[orient="horizontal"] scrollbarbutton:hover {\
background-image: '+cs_buttons_hover_image_horizontal+' !important;\
}\
'), null, null);
ss.loadAndRegisterSheet(uri, ss.AGENT_SHEET);
}
};
var cs_scrollbars_scrollbar_button_arrows = {
init: function() {
var uri = Services.io.newURI("data:text/css;charset=utf-8," + encodeURIComponent('\
\
@namespace html url("http://www.w3.org/1999/xhtml");\
\
scrollbar scrollbarbutton, \
scrollbar[orient="vertical"] scrollbarbutton,\
scrollbar[orient="horizontal"] scrollbarbutton, \
scrollbar[orient="vertical"] scrollbarbutton:hover,\
scrollbar[orient="horizontal"] scrollbarbutton:hover {\
background-color: unset !important;\
background-image: unset !important;\
border-radius: 0px !important;\
}\
scrollbar[orient="vertical"] > scrollbarbutton {\
min-height: '+(custom_scrollbar_size_value/cs_arrows_on_buttons_buttons_size)+'px !important;\
height: '+(custom_scrollbar_size_value/cs_arrows_on_buttons_buttons_size)+'px !important;\
max-height: '+(custom_scrollbar_size_value/cs_arrows_on_buttons_buttons_size)+'px !important;\
min-width: '+custom_scrollbar_size_value+'px !important;\
width: '+custom_scrollbar_size_value+'px !important;\
max-width: '+custom_scrollbar_size_value+'px !important;\
}\
scrollbar[orient="horizontal"] > scrollbarbutton {\
min-width: '+(custom_scrollbar_size_value/cs_arrows_on_buttons_buttons_size)+'px !important;\
width: '+(custom_scrollbar_size_value/cs_arrows_on_buttons_buttons_size)+'px !important;\
max-width: '+(custom_scrollbar_size_value/cs_arrows_on_buttons_buttons_size)+'px !important;\
min-height: '+custom_scrollbar_size_value+'px !important;\
height: '+custom_scrollbar_size_value+'px !important;\
max-height: '+custom_scrollbar_size_value+'px !important;\
}\
scrollbar[orient="vertical"] > scrollbarbutton[type="decrement"] {\
border-left: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-right: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-bottom: '+(custom_scrollbar_size_value/2)+'px solid '+cs_buttons_color+' !important;\
}\
scrollbar[orient="vertical"] > scrollbarbutton[type="decrement"]:hover {\
border-bottom: '+(custom_scrollbar_size_value/2)+'px solid '+cs_buttons_hover_color+' !important;\
}\
scrollbar[orient="vertical"] > scrollbarbutton[type="increment"] {\
border-left: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-right: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-top: '+(custom_scrollbar_size_value/2)+'px solid '+cs_buttons_color+' !important;\
}\
scrollbar[orient="vertical"] > scrollbarbutton[type="increment"]:hover {\
border-top: '+(custom_scrollbar_size_value/2)+'px solid '+cs_buttons_hover_color+' !important;\
}\
scrollbar[orient="horizontal"] > scrollbarbutton[type="decrement"] {\
border-top: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-bottom: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-right: '+(custom_scrollbar_size_value/2)+'px solid '+cs_buttons_color+' !important;\
}\
scrollbar[orient="horizontal"] > scrollbarbutton[type="decrement"]:hover {\
border-right: '+(custom_scrollbar_size_value/2)+'px solid '+cs_buttons_hover_color+' !important;\
}\
scrollbar[orient="horizontal"] > scrollbarbutton[type="increment"] {\
border-top: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-bottom: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-left: '+(custom_scrollbar_size_value/2)+'px solid '+cs_buttons_color+' !important;\
}\
scrollbar[orient="horizontal"] > scrollbarbutton[type="increment"]:hover {\
border-left: '+(custom_scrollbar_size_value/2)+'px solid '+cs_buttons_hover_color+' !important;\
}\
\
'), null, null);
ss.loadAndRegisterSheet(uri, ss.AGENT_SHEET);
}
};
var cs_scrollbars_arrows_on_buttons = {
init: function() {
var uri = Services.io.newURI("data:text/css;charset=utf-8," + encodeURIComponent('\
\
@namespace html url("http://www.w3.org/1999/xhtml");\
\
scrollbar scrollbarbutton, \
scrollbar[orient="vertical"] scrollbarbutton,\
scrollbar[orient="horizontal"] scrollbarbutton, \
scrollbar[orient="vertical"] scrollbarbutton:hover,\
scrollbar[orient="horizontal"] scrollbarbutton:hover {\
border-radius: 0px !important;\
}\
\
scrollbar[orient="vertical"] > scrollbarbutton {\
min-height: '+(custom_scrollbar_size_value/cs_arrows_on_buttons_buttons_size)+'px !important;\
height: '+(custom_scrollbar_size_value/cs_arrows_on_buttons_buttons_size)+'px !important;\
max-height: '+(custom_scrollbar_size_value/cs_arrows_on_buttons_buttons_size)+'px !important;\
min-width: '+custom_scrollbar_size_value+'px !important;\
width: '+custom_scrollbar_size_value+'px !important;\
max-width: '+custom_scrollbar_size_value+'px !important;\
}\
scrollbar[orient="horizontal"] > scrollbarbutton {\
min-width: '+(custom_scrollbar_size_value/cs_arrows_on_buttons_buttons_size)+'px !important;\
width: '+(custom_scrollbar_size_value/cs_arrows_on_buttons_buttons_size)+'px !important;\
max-width: '+(custom_scrollbar_size_value/cs_arrows_on_buttons_buttons_size)+'px !important;\
min-height: '+custom_scrollbar_size_value+'px !important;\
height: '+custom_scrollbar_size_value+'px !important;\
max-height: '+custom_scrollbar_size_value+'px !important;\
}\
scrollbar[orient="vertical"] > scrollbarbutton[type="decrement"] {\
border-left: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-right: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-bottom: '+(custom_scrollbar_size_value/2)+'px solid '+cs_arrows_on_buttons_color+' !important;\
}\
scrollbar[orient="vertical"] > scrollbarbutton[type="decrement"]:hover {\
border-bottom: '+(custom_scrollbar_size_value/2)+'px solid '+cs_arrows_on_buttons_hover_color+' !important;\
}\
scrollbar[orient="vertical"] > scrollbarbutton[type="increment"] {\
border-left: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-right: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-top: '+(custom_scrollbar_size_value/2)+'px solid '+cs_arrows_on_buttons_color+' !important;\
}\
scrollbar[orient="vertical"] > scrollbarbutton[type="increment"]:hover {\
border-top: '+(custom_scrollbar_size_value/2)+'px solid '+cs_arrows_on_buttons_hover_color+' !important;\
}\
scrollbar[orient="horizontal"] > scrollbarbutton[type="decrement"] {\
border-top: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-bottom: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-right: '+(custom_scrollbar_size_value/2)+'px solid '+cs_arrows_on_buttons_color+' !important;\
}\
scrollbar[orient="horizontal"] > scrollbarbutton[type="decrement"]:hover {\
border-right: '+(custom_scrollbar_size_value/2)+'px solid '+cs_arrows_on_buttons_hover_color+' !important;\
}\
scrollbar[orient="horizontal"] > scrollbarbutton[type="increment"] {\
border-top: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-bottom: '+(custom_scrollbar_size_value/2)+'px solid transparent !important;\
border-left: '+(custom_scrollbar_size_value/2)+'px solid '+cs_arrows_on_buttons_color+' !important;\
}\
scrollbar[orient="horizontal"] > scrollbarbutton[type="increment"]:hover {\
border-left: '+(custom_scrollbar_size_value/2)+'px solid '+cs_arrows_on_buttons_hover_color+' !important;\
}\
\
'), null, null);
ss.loadAndRegisterSheet(uri, ss.AGENT_SHEET);
}
};
var scrollbar_buttons = {
init: function() {
var uri = Services.io.newURI("data:text/css;charset=utf-8," + encodeURIComponent('\
\
@namespace html url("http://www.w3.org/1999/xhtml");\
\
scrollbar scrollbarbutton {\
opacity: 0 !important;\
}\
scrollbar[orient="vertical"] scrollbarbutton {\
min-height: 1px !important;\
height: 1px !important;\
max-height: 1px !important;\
}\
scrollbar[orient="horizontal"] scrollbarbutton {\
min-width: 1px !important;\
width: 1px !important;\
max-width: 1px !important;\
}\
\
'), null, null);
ss.loadAndRegisterSheet(uri, ss.AGENT_SHEET);
}
};
var scrollbar_size = {
init: function() {
var uri = Services.io.newURI("data:text/css;charset=utf-8," + encodeURIComponent('\
\
@namespace html url("http://www.w3.org/1999/xhtml");\
\
scrollbar[orient="vertical"] scrollbarbutton {\
min-width: 0 !important;\
width: '+custom_scrollbar_size_value+'px !important;\
max-width: '+custom_scrollbar_size_value+'px !important;\
}\
scrollbar[orient="horizontal"] scrollbarbutton {\
min-height: 0 !important;\
height: '+custom_scrollbar_size_value+'px !important;\
max-height: '+custom_scrollbar_size_value+'px !important;\
}\
\
'), null, null);
ss.loadAndRegisterSheet(uri, ss.AGENT_SHEET);
}
};
var floating_scrollbars = {
init: function() {
var uri = Services.io.newURI("data:text/css;charset=utf-8," + encodeURIComponent('\
\
@namespace html url("http://www.w3.org/1999/xhtml");\
\
scrollbar {\
position: relative !important;\
z-index: 1000000000 !important;\
}\
scrollbar[orient="vertical"],\
scrollbar[orient="horizontal"],\
scrollbar, scrollcorner {\
background-color: transparent !important; \
background-image: unset !important; \
}\
scrollbar[orient="vertical"] {\
-moz-margin-start: -'+custom_scrollbar_size_value+'px !important;\
width: '+custom_scrollbar_size_value+'px !important;\
}\
scrollbar[orient="horizontal"] {\
margin-top: -'+custom_scrollbar_size_value+'px !important;\
height: '+custom_scrollbar_size_value+'px !important;\
}\
\
'), null, null);
ss.loadAndRegisterSheet(uri, ss.AGENT_SHEET);
}
};
var scrollbar_opacity = {
init: function() {
var uri = Services.io.newURI("data:text/css;charset=utf-8," + encodeURIComponent('\
\
@namespace html url("http://www.w3.org/1999/xhtml");\
\
scrollbar {\
opacity: '+custom_opacity_value+' !important;\
}\
\
'), null, null);
ss.loadAndRegisterSheet(uri, ss.AGENT_SHEET);
}
};
var remove_scrollbars = {
init: function() {
var uri = Services.io.newURI("data:text/css;charset=utf-8," + encodeURIComponent('\
\
@namespace html url("http://www.w3.org/1999/xhtml");\
\
scrollbar, scrollcorner {\
display: none !important;\
visibility: collapse !important;\
}\
\
'), null, null);
ss.loadAndRegisterSheet(uri, ss.AGENT_SHEET);
}
};
// enable settings as configured above
if(enable_custom_scrollbars==true) custom_scrollbars.init();
if(cs_buttons_as_arrows==true && hide_scrollbars==false) cs_scrollbars_scrollbar_button_arrows.init();
if(cs_arrows_on_buttons==true && cs_buttons_as_arrows==false && hide_scrollbars==false) cs_scrollbars_arrows_on_buttons.init();
if(hide_scrollbar_buttons==true) scrollbar_buttons.init();
if(custom_scrollbar_size==true) scrollbar_size.init();
if(enable_scrollbars_on_top_of_webcontent==true) floating_scrollbars.init();
if(custom_scrollbar_opacity==true) scrollbar_opacity.init();
if(hide_scrollbars==true) remove_scrollbars.init();Da kannst du allerlei Anpassungen an deine Wünsche vornehmen... 
Oder du versuchst mal folgendes Skript:
Da kannst du allerlei Anpassungen an deine Wünsche vornehmen...
Das ist ja perfekt. Besten Dank 
Gerne!
