https://www.simpleplanes.com/Forums/View/700352/Dark-theme-script

SPtweaks.js

// ==UserScript==
// @name         simpleplanes.com tweaks
// @version      0.2
// @include http://simpleplanes.com/*
// @include https://simpleplanes.com/*
// @include http://www.simpleplanes.com/*
// @include https://www.simpleplanes.com/*
// @author       WNP78
// ==/UserScript==

var style = `


/* Aircraft Post Pop-out */

.post-block { transition: all .2s cubic-bezier(.68,-0.55,.27,1.55); }
.post-block:hover { transform: scale(1.1,1.1); }
/* Basic dark theme */

body {
    background: linear-gradient( rgba(0, 0, 0, 0.8), rgba(0, 0, 0, 0.8) ), url('/Content/img/patterns/gray_jean.png') !important;
    color: #dedede;
}
.body {
    background: #272727 !important;
    border-top-color: #272727 !important;
}
.body header {
    background: #272727 !important;
}
a { color: #079ae4; }
h1, h2, h3, h4, h5, h6 {
    color: #cfcfcf !important;
}
h3, h4, h5 {
    color: #20b3fc !important;
}
p { color: #dedede; }
code, pre {
    background-color: #2d2d2d;
    color: white;
    border-color: #4a4a4a;
    margin: 7px 0px;
}
blockquote {
    background: rgba(0,0,0,0.2) !important;
    border-radius: 3px !important;
    border-left: 5px solid #797979 !important;
}
/* Dividers */
hr {
    background-image: -webkit-linear-gradient(left,transparent,rgba(255,255,255,.65),transparent) !important;
    background-image: linear-gradient(to right,transparent,rgba(255, 255, 255, 0.65),transparent) !important;
}

/* Controls */
.btn-default {
    color: white;
    background: #777;
    border-color: #777;
}
.btn-default:hover, .btn-default:focus, .btn-default:active {
    color: white !important;
    background: #666 !important;
    border-color: #666 !important;
}
.pagination > li > a, .pagination > li > span, .pagination > li > a:hover, .pagination > li > span:hover {
    background: #232323;
    border-color: #232323;
}
.dropdown-menu {
    background: #4d4d4d;
    border-color: #4d4d4d;
    color: white !important;
}
.dropdown-menu > li > a {
    background: #4d4d4d !important;
    border-color: #4d4d4d !important;
    color: white !important;
}
.dropdown-menu > li > a:hover {
    background: #555 !important;
    border-color: #555 !important;
    color: white !important;
}
.modal-content { background-color: #333131 !important; }
.label-success {
    background: #1e9c1e;
}
.label-default {
    background: #666;
}
.form-control[disabled], .form-control[readonly], fieldset[disabled] {
    background-color: #333 !important;
    color: #AAA;
}
input, .form-control {
    background-color: #666;
    border-color: #222;
    color: #FFF;
    border-width: 1px;
    padding: 6px 12px;
    border-radius: 4px;
    width: 100%;
}
.tag-item {
    background: #484848 !important;
}
.tag-item:hover {
    background: #686868 !important;
}

/* SP specific */
div.strikes {
    background-color: #353535 !important;
}
h2.strikes-header {
    color: #ff2626 !important;
    font-weight: bold;
    content: none;
}
body.boxed .body {
  border-bottom: 5px solid #0c0c0c !important;
}
.product-thumb-info {
    background: #1a1a1a !important;
    border-color: #1a1a1a !important;
}
.product-thumb-info.unread {
    background-color: #00334d !important;
}
.product-thumb-info h4 {
    color: white;
}
.forum-list-votes {
    background: #474747;
    color: #ffaa3e;
}
.notification {
    background: #4d4d4d;
    border-color: transparent !important;
}
.notification p {
    color: white;
}
.notification:hover {
    background: #7d7d7d;
}
.post-body {
    background: #4d4d4d;
    border-color: #4d4d4d;
}
ul.comments .comment-block {
    background: #3c3c3c;
}
ul.comments .pinned .comment-block {
    background-color: #2f3640;
}
.downloads {
    color: #c8c8c8;
}
.user-detail {
    background: #444;
}
ul.comments .comment-arrow {
    border-right-color: #3c3c3c;
}
ul.comments .pinned .comment-arrow {
    border-right-color: #2f3640;
}
.comment .label-primary {
    background-color: #08c;
}
.img-thumbnail {
    background: #3f3f3f;
    border-color: transparent;
}
#header nav ul.nav-main ul.dropdown-menu > li > a { border:none; }
.shop table.cart td {
    border-top: 4px solid #2d2d2d;
    padding: 6px 10px;
}
.page-top {
    border-bottom: 5px solid #666
}
a.mention-link {
    background-color: #212121;
    color: white;
    border-radius: 5px;
    padding-left: 3px;
    padding-right: 3px;
    padding-top: 2px;
    padding-bottom: 2px;
}
.post-body img, .post-body video {
    max-width: 100%;
}
.col-md-6 img {
    max-width: 100%;
}
.featured-box {
    background: #444;
    border-color: #555;
    color: #DDD;
}
#new .row {
    background-color: #272727 !important;
}

/* Tables */
.table-striped > tbody > tr:nth-child(2n+1) > td, .table-striped > tbody > tr:nth-child(2n+1) > th {
    background: #363636;
}
.table > thead > tr > th, .table > tbody > tr > th, .table > tfoot > tr > th, .table > thead > tr > td, .table > tbody > tr > td, .table > tfoot > tr > td {
    border-top: none;
}

/* Custom Point Tags */
.user-points.dev { transition: all .5s linear; }
.user-points.mod { background: linear-gradient(#d2322d, #8f0000) #d2322d; }
.user-points.master { background: linear-gradient(#323030,#181818) #333; border-radius: .25em; }
.user-points.gold { background: linear-gradient(#ecbf4f, #bf8800) #e4b84b; }
.user-points.silver { background: linear-gradient(#8f8f8f, #545454) #797979; }
.user-points.bronze { background: linear-gradient(#786113, #59480f) #786113; }
.user-points.noob { border: none; background: linear-gradient(white, #d2d2d2) white; }

/* Fix usernames in upvote lists */
table.table-striped td:last-child {
    max-width: 220px;
    overflow: hidden;
    text-overflow: ellipsis;
}

`;
// Apply CSS
var css = document.createElement("style");
css.type = "text/css";
css.innerHTML = style;
document.body.appendChild(css);
// Add mention links
Array.prototype.forEach.call(document.getElementsByTagName("a"), function (a) { if (/\/u\/[^\/]*/.test(a.href) && a.innerText.startsWith("@")) { a.classList.add("mention-link"); } });

// Fix aircraft descriptions
var r = document.getElementsByClassName("morecontent");
if (r.length == 1) {
    var sp = r[0].getElementsByTagName("span")[0];
    sp.innerHTML = sp.innerHTML.substr(1);
    var m = document.getElementsByClassName("more")[0];
    m.childNodes[m.childNodes.length - 2].textContent = "";
}

// Re-add the mods button
var main = document.getElementById("mainMenu");
var li = document.createElement("li");
var a = document.createElement("a");
a.href = "/Mods";
a.innerText = "Mods";
li.appendChild(a);
main.children[3].insertAdjacentElement("afterend", li);