Visual Header Background Color

Hi abdulmannan1991 
You can use a workaround like this :

1)Insert a rounded rectangle on the page from the Insert tab (click on Shapes, it will give you various shape options, select rounded rectangle from the drop down).

2)Place the rounded rectangle behind the visual(by clicking on the shape, going to the format tab and selecting "Send backward" till the shape goes behind the visual) and adjust the shape so that it has the same width as the visual. Then it looks like this.

3) You can move the visual up or down depending on the height of the top bar you want

Hope this solves your doubt. Here is the attached .pbix file for reference.

https://nicesoftwaresolutions1-my.sharepoint.com/:u:/g/personal/ameshram_nicesoftwaresolutions_com/ESV7Rh83ci1Drq1z7emxnY4BN_sBji3pr4nWbHMUkvdJmA?e=BiX4Tb

Regards,

Aditya