Setting alternate row's alpha doesn't make it transparent

Describe the bug In the Preferences -> Appearance tab, the alpha channel (transparency) for the "Alternate" row background color is ignored. When a user sets the alternate background color to be transparent, the application disregards the alpha setting and renders the row with an opaque color instead.

To Reproduce

• Open CopyQ and go to Preferences
• Navigate to the Appearance tab.
• In the color table, change the "Alternate" color.
• In the color picker dialog, set the alpha to < 255.

Expected behavior Setting the alpha channel of the "Alternate" background color to < 255 should make the row's background transparent.

Screenshots With both normal and alternate set to rgba(0,0,0,70):

Version, OS and Environment

• CopyQ Clipboard Manager 10.0.0
• Qt: 5.15.16
• KNotifications: 5.116.0
• Compiler: GCC
• Arch: x86_64-little_endian-lp64
• OS: Arch Linux
• WM: Hyprland