Edit: I made one. Its based on:

https://github.com/UserStyles/hacker-news-zenburn-dark

  javascript:(()=>{var s=document.createElement('style');s.innerText=`*{color:#dcdccc!important;background-color:#404040!important}body%3Ecenter%3Etable%3Etbody%3Etr:first-child{background-color:#505050!important}body%3Ecenter%3Etable%3Etbody%3Etr:first-childa:hover{background:#404040!important}code,pre,input,textarea{background:#505050!important}a{color:#7F9F7F!important}.subtext%20a{color:#dcdccc!important}a:visited,a:visited%20span{color:#CC9393!important}a:hover,a:hover%20span{background:#505050!important}%60;document.head.appendChild(s)})();