I am trying to achieve an effect similar to the background reveal with mouse movement as seen here : https://www.luckyfolks.fr/.    I am not really sure how and where to start. The svg code for the blob is:      <svg version="1.1" id="Calque_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px" viewBox="0 0 1920 980" style="enable-background:new 0 0 1920 980;" xml:space="preserve"> <style type="text/css"> .st0{fill:#