You need to set the size of the root element / body. The following CSS, copied from the standalone viewer, will make the viewer take up the entire page:
html {
height: 100%;
}
body {
margin: 0;
padding: 0;
overflow: hidden;
position: fixed;
cursor: default;
width: 100%;
height: 100%;
}
#panorama {
width: 100%;
height: 100%;
}
Most helpful comment
You need to set the size of the root element / body. The following CSS, copied from the standalone viewer, will make the viewer take up the entire page: