<script type='text/javascript' src='https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js'/>
letakkan di atas b:SKIN [STYLE]
/* Dark Mode by hartomy.com */
.hartomySwitch{text-align:center;display:inline-block;align-items:center;padding:0}
.ictoggler.theme{text-align:left;}
.ictoggler .text{color:#5e5e5e;text-transform:uppercase;font-size:.7rem;font-weight:600;padding:5px 0}
.switch{position:relative;display:inline-block}
.switch input{display:none}
.gesek:before{border-radius:100%;background:url("data:image/svg+xml,%3Csvg viewBox='0 0 24 24' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M12,6A6,6 0 0,1 18,12C18,14.22 16.79,16.16 15,17.2V19A1,1 0 0,1 14,20H10A1,1 0 0,1 9,19V17.2C7.21,16.16 6,14.22 6,12A6,6 0 0,1 12,6M14,21V22A1,1 0 0,1 13,23H11A1,1 0 0,1 10,22V21H14M20,11H23V13H20V11M1,11H4V13H1V11M13,1V4H11V1H13M4.92,3.5L7.05,5.64L5.63,7.05L3.5,4.93L4.92,3.5M16.95,5.63L19.07,3.5L20.5,4.93L18.37,7.05L16.95,5.63Z' fill='%235f7dde'/%3E%3C/svg%3E") center /21px no-repeat;transition:0.3s cubic-bezier(0.175,0.885,0.32,1.275),padding 0.3s ease,margin 0.3s ease;position:absolute;content:"";height:24px;width:24px;left:-12px;bottom:-7px;background-color:#fff;box-shadow:rgba(74,74,74,0.5) 0 1px 3px,rgba(45,45,45,0.1) 0 0 0 6px}
.gesek.round{border-radius:34px;cursor:pointer}
.hartodark .gesek:before{position:absolute;content:"";left:-12px;height:24px;width:24px;bottom:-7px;background-color:#fff;background:#95a5a6 url("data:image/svg+xml;base64,PD94bWwgdmVyc2lvbj0iMS4wIj8+CjxzdmcgeG1sbnM9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIiB4bWxuczp4bGluaz0iaHR0cDovL3d3dy53My5vcmcvMTk5OS94bGluayIgdmVyc2lvbj0iMS4xIiBpZD0iQ2FwYV8xIiB4PSIwcHgiIHk9IjBweCIgdmlld0JveD0iMCAwIDQ5OS43MTIgNDk5LjcxMiIgc3R5bGU9ImVuYWJsZS1iYWNrZ3JvdW5kOm5ldyAwIDAgNDk5LjcxMiA0OTkuNzEyOyIgeG1sOnNwYWNlPSJwcmVzZXJ2ZSIgd2lkdGg9IjUxMnB4IiBoZWlnaHQ9IjUxMnB4IiBjbGFzcz0iIj48Zz48cGF0aCBzdHlsZT0iZmlsbDojRDlFM0Q0IiBkPSJNMTQ2Ljg4LDM3NS41MjhjMTI2LjI3MiwwLDIyOC42MjQtMTAyLjM2OCwyMjguNjI0LTIyOC42NGMwLTU1Ljk1Mi0yMC4xNi0xMDcuMTM2LTUzLjUyLTE0Ni44OCAgQzQyNS4wNTYsMzMuMDk2LDQ5OS42OTYsMTI5LjY0LDQ5OS42OTYsMjQzLjcwNGMwLDE0MS4zOTItMTE0LjYwOCwyNTYtMjU2LDI1NmMtMTE0LjA2NCwwLTIxMC42MDgtNzQuNjQtMjQzLjY5Ni0xNzcuNzEyICBDMzkuNzQ0LDM1NS4zNjgsOTAuOTQ0LDM3NS41MjgsMTQ2Ljg4LDM3NS41Mjh6IiBkYXRhLW9yaWdpbmFsPSIjRkZEOTNCIiBjbGFzcz0iYWN0aXZlLXBhdGgiIGRhdGEtb2xkX2NvbG9yPSIjRkZEOTNCIi8+PHBhdGggc3R5bGU9ImZpbGw6I0NDRDFDOSIgZD0iTTQwMS45Miw0Mi43NzZjMzQuMjQsNDMuNTA0LDU0LjgxNiw5OC4yNzIsNTQuODE2LDE1Ny45NTJjMCwxNDEuMzkyLTExNC42MDgsMjU2LTI1NiwyNTYgIGMtNTkuNjgsMC0xMTQuNDQ4LTIwLjU3Ni0xNTcuOTUyLTU0LjgxNmM0Ni44NDgsNTkuNDcyLDExOS4zNDQsOTcuNzkyLDIwMC45MjgsOTcuNzkyYzE0MS4zOTIsMCwyNTYtMTE0LjYwOCwyNTYtMjU2ICBDNDk5LjcxMiwxNjIuMTIsNDYxLjM5Miw4OS42NCw0MDEuOTIsNDIuNzc2eiIgZGF0YS1vcmlnaW5hbD0iI0Y0QzUzNCIgY2xhc3M9IiIgZGF0YS1vbGRfY29sb3I9IiNGNEM1MzQiLz48Zz4KCTxwb2x5Z29uIHN0eWxlPSJmaWxsOiNGRkQ4M0I7IiBwb2ludHM9IjEyOC4xMjgsOTkuOTQ0IDE1NC40OTYsMTUzLjQgMjEzLjQ3MiwxNjEuOTYgMTcwLjgsMjAzLjU2IDE4MC44NjQsMjYyLjI5NiAgICAxMjguMTI4LDIzNC41NjggNzUuMzc2LDI2Mi4yOTYgODUuNDQsMjAzLjU2IDQyLjc2OCwxNjEuOTYgMTAxLjc0NCwxNTMuNCAgIiBkYXRhLW9yaWdpbmFsPSIjRkZEODNCIiBjbGFzcz0iIi8+Cgk8cG9seWdvbiBzdHlsZT0iZmlsbDojRkZEODNCOyIgcG9pbnRzPSIyNzYuODY0LDgyLjg0IDI5MC41MjgsMTEwLjU1MiAzMjEuMTA0LDExNC45ODQgMjk4Ljk3NiwxMzYuNTUyIDMwNC4yMDgsMTY2Ljk4NCAgICAyNzYuODY0LDE1Mi42MTYgMjQ5LjUyLDE2Ni45ODQgMjU0Ljc1MiwxMzYuNTUyIDIzMi42MjQsMTE0Ljk4NCAyNjMuMiwxMTAuNTUyICAiIGRhdGEtb3JpZ2luYWw9IiNGRkQ4M0IiIGNsYXNzPSIiLz4KPC9nPjwvZz4gPC9zdmc+Cg==") center / 17px no-repeat;box-shadow:rgb(182, 200, 212) 0 0px 8px, rgba(0, 0, 0, 0.16) 0 0 0 8px;}
@media screen and (max-width:736px){.gesek:before{height:35px;width:35px;left:-12px;bottom:0}.hartodark .gesek:before{height:35px;width:35px;left:-12px;bottom:0}}
.hartodark .Read-more:before{background:url("data:image/svg+xml,%3Csvg viewBox='0 0 24 24' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M22,3H5A2,2 0 0,0 3,5V9H5V5H22V19H5V15H3V19A2,2 0 0,0 5,21H22A2,2 0 0,0 24,19V5A2,2 0 0,0 22,3M7,15V13H0V11H7V9L11,12L7,15M20,13H13V11H20V13M20,9H13V7H20V9M17,17H13V15H17V17Z' fill='%23fff'/%3E%3C/svg%3E") center no-repeat;}
.hartodark body{background:#121212;color:#fff}
.hartodark #header-wrapper{background:#232323;color:#fff}
.hartodark{background:#252f36;color:#fff}
.hartodark a{color:#eee;}
.hartodark .class-baru{}
.hartodark #id-baru{}
untuk tombol nya
<div class='hartomySwitch'>
<div class='switchtheme'>
<div class='theme ictoggler'>
<label class='switch' for='hartodark'>
<input id='hartodark' type='checkbox'/>
<div class='gesek round'/>
</label>
</div>
</div>
</div>
LETAKKAN DI ATAS /BODY
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https://www.hartomy.com/2019/12/cara-membuat-dark-mode-keren-di-semua.html