Sources:

• Snow flakes: https://divilife.com/add-falling-snowflakes-divi-wordpress-website/
• Confetti: https://almostinevitable.com/divi-tutorial-confetti-in-the-background/

Add the snowflakes images to WordPress, I uploaded them with FTP into the /uploads/snowflakes/ folder so they are not in the media library. Add the following CSS to the theme options to show them site wide. For a single page you only add it to the custom css of that page.

/* -- START Snowflakes -- */
body {
position: relative;
}

body:before {
content: '';
   display: block;
   position: absolute;
   z-index: 999999999999999 !important;
   top: 0;
   left: 0;
   right: 0;
   bottom: 0;
   pointer-events: none;
background-image: url('/wp-content/uploads/snowflakes/snowflakes-a.png?dl=1'),
url('/wp-content/uploads/snowflakes/snowflakes-b.png?dl=1'),
url('/wp-content/uploads/snowflakes/snowflakes-c.png?dl=1');	
	-webkit-animation: snow 15s linear infinite;
	-moz-animation: snow 15s linear infinite;
	-ms-animation: snow 15s linear infinite;
	animation: snow 15s linear infinite;
  
}
@keyframes snow {
  0% {background-position: 0px 0px, 0px 0px, 0px 0px;}
  50% {background-position: 500px 500px, 100px 200px, -100px 150px;}
  100% {background-position: 500px 1000px, 200px 400px, -100px 300px;}
}
@-moz-keyframes snow {
  0% {background-position: 0px 0px, 0px 0px, 0px 0px;}
  50% {background-position: 500px 500px, 100px 200px, -100px 150px;}
  100% {background-position: 400px 1000px, 200px 400px, 100px 300px;}
}
@-webkit-keyframes snow {
  0% {background-position: 0px 0px, 0px 0px, 0px 0px;}
  50% {background-position: 500px 500px, 100px 200px, -100px 150px;}
  100% {background-position: 500px 1000px, 200px 400px, -100px 300px;}
}
@-ms-keyframes snow {
  0% {background-position: 0px 0px, 0px 0px, 0px 0px;}
  50% {background-position: 500px 500px, 100px 200px, -100px 150px;}
  100% {background-position: 500px 1000px, 200px 400px, -100px 300px;}
}
/* -- END Snowflakes -- */Code language: CSS (css)

For a single row, section or module, change ‘body’ from the first part into a css class like below and add that class in the row, section or module.

.hws-snow {
position: relative;
}
.hws-snow:after {Code language: CSS (css)