Why div can't occupy the desired width space?

I found if I specify div with only width CSS attribute, the div will not occupy the width I claimed, see:

                <div style="width: 300px;">    
                </div>

It will never occupy 300px space.

Is it possible that I want开发者_C百科 an empty DIV occupies 300px width?

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You either need to add content or set a height. Otherwise an empty div will not appear because its height is determined by its contents.

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See Example

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You need to specify something or a space to achieve that:

<div style="width:300px; border:1px solid black;">&nbsp;</div>

The border was given to show width but you can remove it.

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height must be specified in order to make it visible.