With Microsoft’s new Fluent Design, announced alongside the Fall Creators Update, Windows 10 is gaining more and more transparency—or, technically, translucency. If you don’t like this effect, you can flip a switch to disable transparency in all parts of Windows 10, from the taskbar and Start menu to apps like Calculator and People.
To find this option, open the Settings app from your Start menu.
Click or tap the “Personalization” icon in the Settings window.
Select “Colors” at the left side of the Settings window and scroll down to the More options section. Set the “Transparency effects” slider to “Off”.
At the moment, this option is all or nothing. There’s just a single switch that controls all the transparency effects across the entire operating system. If you want the transparency effect in the Start menu and taskbar, you’ll have to allow it in apps. Microsoft may or may not allow more fine-grained control in the future.