Smarter Themes

pi Scrollbar wp is fully customizable wordpress scrollbar plugin.You can change scrollbar color, border radius, scroll speed, width, border style & other settings using plugin option page.
 Plugin Features
<ul>
<li>Simple installation & activation</li>
<li>Unlimited colors.</li>
<li>CSS3 animation.</li>
<li>Supported touch devices.</li>
<li>All browser supported</li>
<li>Custom Width.</li>
<li>Scrollbar border radius.</li>
<li>Scrollbar scroll speed.</li>
<li>Scrollbar border.</li>
<li>Auto Hide Enable/Disable Mode.</li>
<li>Lightweight Responsive.</li>
<li>Easy Option Panel.</li>
<li>Easy Documentation.</li>
</ul>

Scrollbar

Customize your browser scrollbars with unlimited styling and color using scrollbar wp plugin.

joydevpal

JP Scrollbar is a wordpress plugin for your wordpress website. You can easily replace your default scrollbar with a nice looking scrollbar. To use this plugin you need to install the plugin and activate. Easy enough!
You can change your scrollbar theme, scroll speed, autohide mode, keyboard scrolling etc.
 Other Features 
<ul>
<li>Super Easy Installation </li>
<li>Very Lightweight, Only 40KB</li>
<li>Supports multiple scrollbar theme</li>
<li>All mejor browser supported</li>
<li>Responsive for all devices </li>
<li>Works with 3.3+ version of WordPress</li>
<li>Settings Customization</li>
</ul>

JP Scrollbar

JP Scrollbar is a WordPress plugin that enables a awesome scrollbar instead default scrollbar.

Scrollbar vs JP Scrollbar