When viewing an activity on Garmin Connect, the map has a fixed height. Especially on larger screens, you may want to view a larger map, but there is no built-in option to resize the map.
Using this bookmarklet, you can view the map in the full browser window.
You may have to zoom in and out (Ctrl+, Ctrl-) to trigger the map to adapt to the new size.
The bookmarklet runs this JavaScript code:
javascript:(function(){ var e = document.getElementById('activity-map-canvas'); if (!e) { alert('No map element found'); return; } if (e.style.position === 'relative') { e.style.position = 'fixed'; e.style.top = 0; e.style.left = 0; e.style.right = 0; e.style.height ='100%'; e.style.zIndex = 100; } else { e.style.height='400px'; e.style.position = 'relative' } })();