The Elements panel turns your Replay video into an interactive web application. It displays the entire HTML of the page. You can hover over an element and you'll see it highlighted in the video panel above. You can also use the Element Selector above the panel to highlight any section of the app in the video panel and it will focus that element below.

In addition, you can see all of the CSS rules currently applied to that element as well as a layout visualization showing you the element's height, width, margin, padding and border.

Finally, you can see the Computed section which displays the currently applied styles to an element after the CSS specificity rules have been applied.