At one point in time, I clicked on a desktop icon to open a certain website

With the arrows on both sides... I pulled in the page, to be narrower... so that I could open another page... doing the same thing... in order to compare two photos side by side

Now every time I open my browser... or a web site from an icon on my desktop... the window opens narrow... maybe about one third the width of my screen

Vertically the window opens fully... but horizontally, the borders are pulled in and narrows the window's width

I can't seem to correct this

Many thanks