How do I change back color for header bar in ionic?

Hello,I am new to Ionic.

I write code like (filename: home.html):

In output content is displayed but color is not changed…

I have used blank template and I am using ionic version 3.6.0.

In app.scss

         background-color:#34495e !important;
         color:white !important;
        color:white !important;

thanks a lot…
but I want to know if I am changing in above manner (as in my query post) why this is not worked!! due to versioning issue or any other…