Block Safari from Resizing Website on iPad

I have set up a new website which looks perfect on all browsers on desktops, and even on opera browser on iPad.

But Safari on iPad tries to resize the top half of the website, making the header narrower than content below. As if top half has moved to the left by half an inch.

I am told there is a line of code you can put in the CSS body that tells Safari and Apple NOT to try and reize the website for mobile devices.

Does anyone know what the code is and where I put it?