It is possible to move the page area down when it's viewed in a web browser, so rather then the top of the page being at the top of the visible area within the browser you can set a top margin which moves the page area down.
To set the top page margin first make a note of your page height by going to Utilties - Options - Page Size tab.
Then go to the Grid & Ruler tab and change the Origin (0,0 point) for the Y axis to a value larger than your page height value.
For example if your page height is 700px, by setting the Y axis origin point to 720px will give the page a 20px top margin when it's viewed in a browser.
If you are applying this once you have got multiple pages in your document, you will need to set this for each page individually.
Note that this top margin is displaying the pasteboard area, so therefore objects placed on this area shall not be displayed because they are off of the page area.