You can do it like this:
Code:
<body >
<div style="width: 100%;">
<img alt="Image" src="../Images/map.jpeg" />
</div>
</body>
Also, I remember that if you know the width and height of an image beforehand, then adding them to the image is (maybe... was?) good practice, as it would make it faster for a browser to lay out a page.
Don't quote me on this; I've not done serious front-end web development for some years now.