Course Presentation - Visible Screen Size

Hi,  why would the visible screen size on Course Presentation be slightly short of 100% both width and height? It leaves a gap right and bottom, not allowing an image to completely fill the presentation area, screenshot attached.

(I also find it strange that an image pre-sized to be full-size image is imported into the image area at a fraction of the size, meaning you have to stretch it back out again. The smaller image isn't always exactly the same image ratio to the original, we are talking tiny percentages out).

<div class="h5p-element h5p-element-button-big h5p-transparent" style="left: 0%; top: 0%; width: 99.7805%; height: 99.5662%;"><div class="h5p-element-outer h5p-image-outer-element" style="background: rgba(255, 255, 255, 0);"><div class="h5p-element-inner h5p-image"><img src="http://localhost:8888/moodle36/pluginfile.php/59/mod_hvp/content/6/image..." alt="New image" title="Untitled Image" style="width: 100%; height: 100%;"></div></div></div>