Missing arrows on top and bottom of custom scrollbar track

Question

I am working on the code below. Why am I missing the arrows on top and bottom of the custom scrollbar tracker to have like

div{
max-width:150px;
max-height:200px;
 overflow-y: scroll;
  overflow-x: hidden;
}
div::-webkit-scrollbar {
  width: 1em;
}

div::-webkit-scrollbar-track {
  -webkit-box-shadow: inset 0 0 2px rgba(0,0,0,0.3);
  }
  
div::-webkit-scrollbar-thumb {
  background-color: darkgrey;
  outline: 1px solid slategrey;
}

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Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
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Answer 1

for custom scrollbar tracker you need to add style ::-webkit-scrollbar-button pseudo element. like this.

div{
max-width:150px;
max-height:200px;
 overflow-y: scroll;
  overflow-x: hidden;
}
div::-webkit-scrollbar {
  width: 1em;
}

div::-webkit-scrollbar-track {
  -webkit-box-shadow: inset 0 0 2px rgba(0,0,0,0.3);
  }
  
div::-webkit-scrollbar-thumb {
  background-color: darkgrey;
  outline: 1px solid slategrey;
}

::-webkit-scrollbar-button {
    background-color: red;
    background-size: 10px 10px;
    background-repeat: no-repeat;
    background-position: center center;
    height: 16px;
    width: 1em;
    -webkit-box-shadow: inset 1px 1px 2px rgba(0,0,0,0.2);
}

::-webkit-scrollbar-button:horizontal:increment {
    background-image: url(https://dl.dropboxusercontent.com/u/55165267/icon2.png);
}

::-webkit-scrollbar-button:end:increment {
    background-image: url(data:image/svg+xml;utf8;base64,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);
}
 

::-webkit-scrollbar-button:start:decrement {
   background-image: url(data:image/svg+xml;utf8;base64,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)
}

<div>

Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
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