手抜き退避ですみません ^-^;;
以下コピペ用です
①https://chrome.google.com/webstore/detail/stylish-custom-themes-for/fjnbnpbmkenffdnngjfgmeleoegfcffe?hl=ja
②https://www.tokyomotion.net/user/ta300/videos
⑤
.img-private {
-webkit-filter: brightness();
-moz-filter: brightness(0.3);
-o-filter: brightness(0.3);
-ms-filter: brightness(0.3);
}