Please ignore those dark lines. It doesn't exists. It exists when I took photo of my screen from another old phone of someone else.
That thick white is existing since last 2 weeks. Since last 2 days, a purplish botch has emerged at the right bottom of the screen where you can se the back sign button.
I don't know what it does means. I wish I could resolve it on my own. Two months ago, I got my screen replaced.