GoldenDict Dark Theme

article-style.css

body
{
  margin-top: 1px;
  margin-right: 3px;
  margin-left:  2px;
  margin-bottom: 3px;
  background: #201F1F;
  color: white;
  font-family: Bookerly, Segoe UI, Palatino Linotype, Arial Unicode MS;
}

a:link
{
  color: orange;
}

ul
{
  color: white;
}

.gdarticle
{
  background: #201F1F;
  color: white;
  margin-top: 0.1em;
  margin-bottom: 0.4em;
  padding: 5px;
  border: 1px solid white;
}

.gdactivearticle
{
  border: 1px solid #3399FF;
}

.gdarticleseparator + script + .gdactivearticle .gddictname
{
  border-top: 1px solid #3399FF;
}

.gdarticleseparator
{
  display: none;
}

.gddictname
{
  background: #000000;
  font-size: 14px;
  font-weight: normal;
  float: right;
  border: 0px;
  margin: -6px;
  margin-bottom: 5px;
  margin-left: 2px;
  padding-right: 0.4em;

  -webkit-user-select: none;
  user-select: none;
  cursor: default;
}

.gdactivearticle .gddictname
{
  font-size: 14px;
  font-weight: normal;
  margin: -6px;
  margin-bottom: 5px;
  margin-left: 2px;

  float: right;
  border: 1px solid white;
}

.gddicticon
{
  display: inline;
  vertical-align: text-bottom;
  float: right;
  padding-right: 0em;
  padding-left: 0.3em;
}

/**
 * Old Dictionaries using DSL format
 */
.gdarticlebody > span:first-child .dsl_headwords,
.gdarticlebody > h3:first-child
{
  margin-top: -3px;
  display: inline-block;
}

.gdspellsuggestion
{
  /* Add some vertical space before the article */
  margin-top: 1.5em;
}

.dsl_article, .dsl_definition, .dsl_ex, .dsl_opt, .dsl_lang, .dsl_m0, .dsl_m1, .dsl_m2, .dsl_m3, .dsl_m4, .dsl_u, .dsl_b, .dsl_i
{
  color: white !important;
}

.dsl_p {
  color: #FF7400 !important;
}

.dsl_b font {
  color: #FFD300 !important;
}

.dsl_m2 font {
  color: #71FF35 !important;
}

.dsl_i font {
  color: white !important;
}

.dsl_article .dsl_definition {
  color: #FFEA13 !important;
}

.dsl_article .dsl_definition font[color="darkcyan"]
{
  color: #FFEA13 !important;
}

.dsl_article .dsl_definition font[color="teal"]
{
  color: #FFEA13 !important;
}

.dsl_article .dsl_definition font[color="darkslategray"]
{
  color: #E7003E !important;
}

.dsl_article .dsl_definition font[color="darkslateblue"]
{
  color: #E7003E !important;
}

.dsl_article .dsl_definition font[color="darkmagenta"]
{
  color: #E7003E !important;
}

.dsl_article .dsl_definition font[color="sienna"]
{
  color: #E7003E !important;
}

.dsl_article .dsl_definition font[color="rosybrown"]
{
  color: #E7003E !important;
}

.dsl_article .dsl_definition font[color="dimgray"]
{
  color: white !important;
}

.dsl_article .dsl_definition font[color="green"]
{
  color: #E7003E !important;
}

.dsl_article .dsl_definition font[color="darkgreen"]
{
  color: #E7003E !important;
}

::selection
{
  background: yellow;
	color: white;
}

code::selection
{
	background: white;
}

.dsl_s_wav img, .lsa_play img, .forvo_play img[alt="Play"]
{
  /**
  display: none;
  **/
}

.dsl_s_wav a, .lsa_play td:nth-of-type(1) a, .forvo_play td:nth-of-type(1) a
{
  color: white;
  width: 18px;
  height: 14px;
  /**
  display: inline-block;
  background: url('file:///control_play_lingvo.png') no-repeat center;
  vertical-align: text-bottom;
  -webkit-user-select: none;
  user-select: none;
  **/
}

/**
 * OALD9 Dictionary
 */

.mdict, .mdict ol, .head-jump-pos, .head-jump-entry, .h-g, sn-gs, .sn-g, .x-gs, .xg, .rx-g, .x, .num, .def, .label-g, .collapse
{
  color: white !important;
}

.head-jump-pos a
{
  display: inline-block;
  background-color: green;
  color: white !important;
  padding-top: 2px;
  padding-bottom: 3px;
  padding-left: 5px;
  padding-right: 5px;
  margin-right: 3px;
  margin-bottom: 3px;
  text-decoration: none;
  font-size: 90%;
  border-radius: 2px;
}

.mdict .if-gs
{
  color: #E7003E !important;
}

.mdict .gram-g
{
  color: #FF7400 !important;
}

.mdict .top-container
{
  line-height: 1.2em !important;
}

.mdict .collapse, .mdict .webtop-g
{
  background-color: #03A9F4 !important;
  border-left: 3px solid #03A9F4 !important;
}

.mdict .collapse .body .h1, .mdict .collapse .body .deflist .li .eb
{
  color: #D32F2F !important;
}

.mdict .collapse .body .inline .li
{
  color: #512DA8 !important;
}

/** Fix numbered list **/
.mdict ol
{
  list-style-type: none;
}

.mdict ol li
{
  counter-increment: step-counter;

}

.mdict ol li::before
{
  content: counter(step-counter);
  color: #E7003E !important;
  font-weight: bold;
}

/** Fix phonetics **/

.mdict .phon {
  color: #E7003E !important;
  font-weight: bold;
}

/**
 * Longman Dictionary 6
 */

.entry, .example, .collocate, .collgloss, .sense, .neutral, .exas li
{
  color: white !important;
}

.hyphenation, .homnum, .frequent
{
  color: #FFEB3B !important;
}

.pron, .amevarpron
{
  color: #D32F2F !important;
  font-weight: bold;
}

.gram, .registerlab
{
  color: #03A9F4 !important;
}

.propformprep, .expr, .colloc, .collo, .exp, .display, .nodeword {
  color: #FF4081 !important;
}

.sensenum
{
  color: #E7003E !important;
}

.collobox
{
  background-color: #448AFF !important;
  border-color: #448AFF !important;
}

.thesbox
{
  background-color: #FFEB3B !important;
  border-color: #FFEB3B !important;
}

.grambox .expl, .grambox .compareword, .collobox .section, .thesbox .section
{
  background-color: #201F1F !important;
}

.secheading
{
  background-color: #1976D2 !important;
}
/**
 * Từ điển Lạc Việt
 */
table, #definition_T_id, #mh_n_T_id, #mh_T_id, #C_C
{
  color: white !important;
}

#C_C font {
  color: white !important;
}

qt-style.css

MainWindow #searchPane #translateLine, MainWindow #searchPane #wordList
{
	background: #201F1F;
	color: #D4D2CF;
}
MainWindow #favoritesPane #favoritesTree
{
	background: #201F1F;
	color: #D4D2CF;
}
MainWindow #translateLine, ScanPopup #translateLine, MainWindow #wordList, MainWindow #dictsPane #dictsList, MainWindow #historyPane #historyList
{
	background: #201F1F;
	color: #D4D2CF
}

I've created the derivation with this style for Nix users:

$ nix-env -iA nur.repos.sikmir.goldendict-dark-theme

Mil gracias.