Rocket.Chat Dark Mode

dark-mode-toggle.js

// Toggleable dark mode for those of us that care about that kind of thing.
const darkModeSymbol = `<svg id="icon-darkmode" viewBox="0 0 468 468" fill="currentColor">
  <path d="m428.75601,300.104c-0.664,-3.81 -2.33401,-7.047 -4.996,-9.71301c-5.89999,-5.90298 -12.75201,-7.142 -20.55399,-3.716c-20.93701,9.70801 -42.64102,14.55801 -65.09702,14.55801c-28.17099,0 -54.15201,-6.94 -77.94299,-20.83801c-23.791,-13.89398 -42.63101,-32.73599 -56.52501,-56.52998c-13.899,-23.793 -20.84399,-49.77299 -20.84399,-77.94499c0,-21.88802 4.33299,-42.68301 12.991,-62.384c8.66,-19.7 21.17599,-36.973 37.543,-51.82c6.283,-5.898 7.713,-12.752 4.287,-20.557c-3.23601,-7.801 -9.041,-11.511 -17.41501,-11.132c-29.12099,1.141 -56.71999,7.664 -82.797,19.556c-26.076,11.89499 -48.48901,27.54699 -67.23801,46.96499c-18.747,19.414 -33.595,42.39899 -44.54,68.94999c-10.942,26.55301 -16.416,54.39 -16.416,83.51102c0,29.694 5.806,58.05399 17.416,85.082c11.613,27.02798 27.218,50.34399 46.824,69.94897c19.604,19.599 42.92,35.207 69.951,46.82202c27.028,11.60699 55.38399,17.41498 85.075,17.41498c42.63998,0 81.987,-11.56299 118.05399,-34.69c36.069,-23.12399 63.05002,-54.00598 80.944,-92.64499c1.52402,-3.42297 1.95102,-7.03598 1.28003,-10.83798zm-122.19101,84.064c-24.646,11.711 -50.67599,17.56201 -78.08701,17.56201c-24.743,0 -48.38998,-4.853 -70.94699,-14.55801c-22.554,-9.70499 -41.97099,-22.69501 -58.24599,-38.97198c-16.271,-16.272 -29.259,-35.686 -38.97,-58.241c-9.707,-22.556 -14.561,-46.20302 -14.561,-70.94801c0,-40.922 12.135,-77.466 36.403,-109.636c24.266,-32.165 55.53099,-53.959 93.78799,-65.379c-19.795,31.405 -29.694,65.379 -29.694,101.926c0,34.644 8.564,66.715 25.69701,96.22301c17.12799,29.49901 40.446,52.81099 69.95,69.94798c29.49899,17.129 61.565,25.694 96.211,25.694c10.65601,0 21.129,-0.85498 31.40799,-2.56998c-17.31799,20.93799 -38.30701,37.25497 -62.952,48.95099z"/>
</svg>`; // moon icon
const lightModeSymbol = `<svg id="icon-darkmode" viewBox="0 0 302.4 302.4" fill="currentColor">
  <path d="m204.8,97.6c-13.60001,-13.6 -32.8,-22.4 -53.60001,-22.4s-40,8.4 -53.6,22.4c-13.6,13.6 -22.4,32.8 -22.4,53.6s8.8,40 22.4,53.59999c13.6,13.60001 32.8,22.40001 53.6,22.40001s40,-8.40001 53.60001,-22.40001c13.59999,-13.59999 22.39999,-32.8 22.39999,-53.59999s-8.39999,-40 -22.39999,-53.6zm-14.40001,92.8c-10,10 -24,16 -39.2,16s-29.2,-6 -39.2,-16s-16,-24 -16,-39.2s6,-29.2 16,-39.2s23.99999,-16 39.2,-16s29.2,6 39.2,16s16,23.99999 16,39.2s-6,29.2 -16,39.2z"/>
  <path d="m292,140.8l-30.79999,0c-5.60001,0 -10.40001,4.8 -10.40001,10.39999c0,5.60001 4.8,10.40001 10.40001,10.40001l30.79999,0c5.60001,0 10.39999,-4.8 10.39999,-10.40001c0,-5.59999 -4.79999,-10.39999 -10.39999,-10.39999z"/>
  <path d="m151.2,250.8c-5.59999,0 -10.39999,4.8 -10.39999,10.40001l0,30.79999c0,5.60001 4.8,10.39999 10.39999,10.39999c5.60001,0 10.40001,-4.79999 10.40001,-10.39999l0,-30.79999c0,-5.60001 -4.8,-10.40001 -10.40001,-10.40001z"/>
  <path d="m258,243.60001l-22,-22c-3.60001,-4 -10.39999,-4 -14.39999,0s-4,10.40001 0,14.40001l22,21.99998c4,4 10.39999,4 14.39999,0s4,-10.39999 0,-14.39999z"/>
  <path d="m151.2,0c-5.59999,0 -10.39999,4.8 -10.39999,10.4l0,30.8c0,5.6 4.8,10.4 10.39999,10.4c5.60001,0 10.40001,-4.8 10.40001,-10.4l0,-30.8c0,-5.6 -4.8,-10.4 -10.40001,-10.4z"/>
  <path d="m258.39999,44.4c-4,-4 -10.40001,-4 -14.40001,0l-22,22c-4,4 -4,10.4 0,14.4c3.60001,4 10.40001,4 14.40001,0l22,-22c4,-4 4,-10.4 0,-14.4z"/>
  <path d="m41.2,140.8l-30.8,0c-5.6,0 -10.4,4.8 -10.4,10.39999s4.4,10.40001 10.4,10.40001l30.8,0c5.6,0 10.4,-4.8 10.4,-10.40001c0,-5.59999 -4.8,-10.39999 -10.4,-10.39999z"/>
  <path d="m80.4,221.60001c-3.6,-4 -10.4,-4 -14.4,0l-22,22c-4,4 -4,10.40001 0,14.39999s10.4,4 14.4,0l22,-21.99998c4,-4.00002 4,-10.40001 0,-14.40001z"/>
  <path d="m80.4,66.4l-22,-22c-4,-4 -10.4,-4 -14.4,0s-4,10.4 0,14.4l22,22c4,4 10.4,4 14.4,0s4,-10.4 0,-14.4z"/>
</svg>`; // sun icon
const toggleButton = '<button class="sidebar__toolbar-button rc-tooltip rc-tooltip--down js-button" aria-label="Toggle Dark Mode">D</button>';

function isDarkModeSet() {
  return localStorage.getItem('dark-mode') === 'true';
}

function getDarkModeIcon() {
  return `<svg class="rc-icon sidebar__toolbar-button-icon sidebar__toolbar-button-icon--darkmode" aria-hidden="true">
    <use xlink:href="#icon-darkmode"></use>
    ${isDarkModeSet() ? lightModeSymbol : darkModeSymbol}
  </svg>`;
}

function toggleDarkMode() {
  document.body.classList.toggle('dark-mode');
  const setting = (!isDarkModeSet()).toString();
  localStorage.setItem('dark-mode', setting);
}

function addDarkModeToggle() {
  const sidebarToolbar = $('.sidebar__toolbar');
  
  // wait for the sidebar toolbar to be visible
  // this will also be false if the toolbar doesn't exist yet
  if(!sidebarToolbar.is(':visible')) {
    setTimeout(addDarkModeToggle, 250);
    return;
  }
  
  var darkModeButton = $('.js-button[aria-label="Toggle Dark Mode"]');
  
  // do nothing if button is already on the screen
  if (darkModeButton.is(':visible')) {
  	return;	
  }
  
  darkModeButton = $(toggleButton).prependTo(sidebarToolbar);
  darkModeButton.html(getDarkModeIcon());
  
  darkModeButton.on('click', function() {
    toggleDarkMode();
    darkModeButton.html(getDarkModeIcon());
  });
}

$(addDarkModeToggle);

// Apply dark mode immediately if it's been set previously
if (isDarkModeSet()) {
  document.body.classList.add('dark-mode');
}

dark-mode.css

:root {
  --primary-font-color: #444;
  --info-font-color: #a0a0a0;
  --sidebar-footer-height: 100px;
}

/* Reset global font color so that it's changable more easily */
.color-primary-font-color, textarea {
  color: var(--primary-font-color);
}

.color-info-font-color {
  color: var(--info-font-color);
}

select {
  color: var(--input-text-color);
}

.error-color {
  color: var(--rc-color-error);
}

.js-button[aria-label="Toggle Dark Mode"] {
  transition: filter 150ms;  
}

/**
 * Transitions for a smooth change into dark mode
 */
textarea,
select,
.color-primary-font-color,
.color-info-font-color,
.messages-box .message .body, /* override for opacity transition */
.rc-header__name,
.rc-header__wrap,
.message .reactions>li,
.message .title .is-bot,
.message .title .role-tag,
.message.new-day::before,
.code-colors,
.hljs-selector-id,
.hljs-selector-tag,
.hljs-attribute,
.hljs-keyword,
.hljs-title,
.hljs-doctag,
.hljs-string,
.hljs-type,
.hljs-literal, 
.hljs-number, 
.hljs-tag .hljs-attr, 
.hljs-template-variable,
.hljs-variable,
.rc-message-box__container,
.messages-container .footer,
.content-background-color,
.message.new-day::after,
.message .reactions>li,
.border-component-color,
.contextual-bar__header,
.contextual-bar__content,
.sidebar__footer {
  transition: opacity 300ms linear, color 150ms, background-color 150ms, border-color 150ms;
}

/**
 * Dark Mode Settings
 */
body.dark-mode {
  --header-background-color: var(--color-darkest);
  --header-title-username-color-darker: var(--color-gray-lightest);
  --primary-font-color: var(--color-gray-lightest);
  --info-font-color: var(--color-gray-light);
  --message-box-typing-user-color: var(--color-gray-light);

  --rc-color-primary: var(--color-gray-lightest);
  --rc-color-primary-lightest: var(--color-dark-medium);
  --rc-color-alert-message-warning-background: hsl(352, 83%, 20%);
  
  --input-text-color: var(--color-gray-lightest);
  --input-icon-color: var(--color-gray-lightest);
  
  --mention-link-text-color: var(--color-light-blue);
  --mention-link-background: var(--color-dark-medium);
}

.sidebar__toolbar-button-icon--darkmode {
    height: .9em;
}

@media (min-width: 1372px) {
    .sidebar__toolbar-button {
        margin: 0 3px;
    }
}

body.dark-mode a {
  color: var(--color-light-blue);
}

body.dark-mode a:visited {
  color: hsl(310, 90%, 70%);
}

body.dark-mode .sidebar-item > a {
  color: inherit;
}

body.dark-mode .emoji-picker {
  background-color: var(--rc-color-primary-dark);
}

body.dark-mode .emoji-picker .filter-item.active {
  border-color: hsl(203, 73%, 52%);
}

body.dark-mode .rc-old .rc-message-box .reply-preview {
  background-color: var(--color-dark);
}

body.dark-mode .message-actions,
body.dark-mode .rc-member-list__counter {
  color: var(--color-gray);
}

body.dark-mode .rc-member-list__user.active,
body.dark-mode .rc-member-list__user:hover {
  background-color: var(--color-darkest);
}

body.dark-mode select option {
  color: var(--color-dark);
}

body.dark-mode .error-border {
  border-color: var(--color-dark-red);
}

body.dark-mode .messages-container .footer,
body.dark-mode .content-background-color {
  background-color: var(--header-background-color);
}

body.dark-mode .message.new-day::after,
body.dark-mode .message .reactions>li,
body.dark-mode .border-component-color {
  border-color: var(--rc-color-primary-lightest);
}

body.dark-mode .js-button[aria-label="Toggle Dark Mode"] {
  filter: brightness(130%);
}

body.dark-mode .message .reactions>li,
body.dark-mode .message .title .is-bot,
body.dark-mode .message .title .role-tag,
body.dark-mode .message.new-day::before {
  background-color: hsl(219, 15%, 33%);
}

body.dark-mode .rc-message-box__container {
  background-color: hsla(0, 0, 100%, 0.1);
}

body.dark-mode .rc-button {
  border-color: var(--color-gray-medium);
  color: var(--color-gray-medium);
}

/* Ensure that colors still come through on buttons in dark mode */
body.dark-mode .rc-button--cancel.rc-button--outline {
  color: #f5455c;
  color: var(--button-cancel-color);
  border-color: #f5455c;
  border-color: var(--button-cancel-color);
}

body.dark-mode .contextual-bar {
  background-color: var(--color-dark);
}

body.dark-mode .contextual-bar__header {
  background-color: var(--color-darkest);
}

body.dark-mode .contextual-bar__content {
  background-color: var(--color-dark);
}

body.dark-mode .message.editing {
  background-color: var(--color-dark-blue);
}

body.dark-mode .rc-popover__content {
  background-color: var(--popover-item-color);
}

body.dark-mode .rc-popover__item-text,
body.dark-mode .rc-popover__icon {
  color: var(--popover-background);
}

/**
 * Code Highlighting
 *
 * Colors based on HipChat highlighting
 */

body.dark-mode .code-colors {
  background: var(--color-dark-100);
  color: var(--color-gray-light);
}

body.dark-mode .hljs-selector-id,
body.dark-mode .hljs-keyword {
  color: var(--color-light-blue);
}

body.dark-mode .hljs-title {
  color: var(--color-gray-light);
}

body.dark-mode .hljs-literal, 
body.dark-mode .hljs-number, 
body.dark-mode .hljs-tag .hljs-attr, 
body.dark-mode .hljs-template-variable, 
body.dark-mode .hljs-variable {
  color: var(--color-dark-green);
}

body.dark-mode .hljs-selector-tag {
  color: var(--color-green);
}

body.dark-mode .hljs-doctag, 
body.dark-mode .hljs-string {
  color: var(--color-red);
}

body.dark-mode .hljs-attribute,
body.dark-mode .hljs-type,
body.dark-mode .hljs-number {
  color: var(--color-orange);
}

/**
 * Admin specific settings
 */
.page-list a:not(.rc-button), .page-settings a:not(.rc-button) {
  color: var(--primary-font-color);
}

body.dark-mode .sidebar-flex__header {
  background-color: var(--color-darkest);
}

body.dark-mode .sidebar-light {
  background-color: var(--color-dark);
}

body.dark-mode .rcx-accordion-item__title,
body.dark-mode .rcx-label__text {
  color: var(--color-white);
}

body.dark-mode .sidebar-flex__search .rc-input__element {
  color: var(--color-dark);
}

body.dark-mode .admin-table-row {
  background-color: hsl(219, 16%, 25%);
}

body.dark-mode .sidebar-light .sidebar-item {
  color: inherit;
}

body.dark-mode .admin-table-row:nth-child(even) {
  background-color: hsl(219, 15%, 33%);
}

body.dark-mode .permissions-manager .permission-grid .id-styler {
  color: var(--info-font-color);
}

To apply to RocketChat:

1. Go to Administration > Layout
2. Copy JS to Custom Scripts > Custom Scripts for Logged In Users
3. Copy CSS to Custom CSS
4. Restart your RocketChat App (server restart not required)