The secret is to use a bookmarklet with the following as the url:

javascript:!function(e){var t="https://boopy.me/pogo/icons-large-sprite.png",r="https://boopy.me/pogo/";localStorage.removeItem("spritefile"),localStorage.removeItem("spritefileLarge"),localStorage.setItem("spritefileLarge",t),localStorage.setItem("weatherSpritesSrc",r),localStorage.getItem("weatherSpritesSrc")===r&&localStorage.getItem("spritefileLarge")===t?alert("Icons updated. Refresh page."):alert("Something went wrong.")}($);


Recording on how to apply it on  mobile but can be done  on desktop also.

https://youtu.be/j9DzV8GkU7E