Unfortunately that's the fault of the web page designer rather than your PC. In the old days web pages were designed to fit a standard 800x600 pixel screen because that's the way computer screens were built. Then they moved up a bit to 1024x768 but they were still all the standard 4:3 aspect ratio.
Now, of course, screens are any old size including wide screen which are 16:9 ratio. Many web page designers kept up with technology and re-designed their pages to automatically expand to fill the available screen space. You will have noticed that this forum hasn't managed to do so yet!!
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Do you know that we're all in line for succession to the throne? Really?
Well, if forty-eight million, two hundred thousand, seven hundred and one people died I'd be Queen.