I think the issue with the accepted answer (thank you for that!) is that one of the prop
erties it tries to transfer on the el
ement style from the Computed Style is the cssText
.
If we exclude from the transfer cssText
and also other properties that are actually methods, it works!
So building on the accepted answer and this answer, I've got:
var el = document.querySelector("#answer-25097808 > div > div.answercell.post-layout--right > div.s-prose.js-post-body > pre"); // change yourId to id of your element, or you can write “body” and it will convert all document
var els = el.getElementsByTagName("*");
for(var i = -1, l = els.length; ++i < l;){
el = els[i]
s = getComputedStyle(el)
for (let styleKey in el.style) {
for (let computedStyleKey in s) {
let computedStyleKeyCamelCase = computedStyleKey.replace(/\-([a-z])/g, v => v[1].toUpperCase());
if ((typeof el.style[styleKey] != "function") && (styleKey != 'cssText')){
if(styleKey == computedStyleKeyCamelCase) {
el.style[styleKey] = s[computedStyleKey];
}
}
}
}
}
P.S.: the above code should run in the Developer Tools console (tried it in Chrome)