Change browser search header color from pink to blue

On macOS 26.6, open Safari >> Settings >> Tabs and turn off Show colour in tab bar. 

When enabled, Safari can use the active webpage’s background colour for the tab bar.

Safari does not appear to provide an option to select a specific custom colour, such as blue, for the tab bar.

Apple: Change Tabs settings in Safari on Mac

If you are using other Web Browser, please provide those details in a response 

What exactly do you mean by "search header?" A screenshot would be helpful.

Also, which browser?