Nucleus Dark UI + Base16[Ocean] + Arc-Dark + Tweaks

styles.less

//
// Arc/Solus Tweaks
//

// Fix keybindings
kbd {
  color: #a9caf1;
  border-color: #a9caf1;
}
// Fix readme code blocks
code {
  color: #a9caf1;
}
// Fix links with base16 ocean syntax
.settings-view .link,
.text-info {
  color: #a9caf1;
}
.settings-view .link:hover {
  color: #a9caf1;
}
.settings-view .alert-info {
  color: white;
  background: #a9caf1;
  border-color: #a9caf1 !important;
}
// fix bracket-matcher
atom-text-editor .bracket-matcher .region,
atom-text-editor::shadow .bracket-matcher .region,
:host .bracket-matcher .region {
  border: 1px solid #a9caf1;
  background-color: rgba(169, 202, 241, 0.32);
}

// Fix button links with base16 ocean syntax
.btn.btn-info,
button.btn-info, button.icon.btn-info, .btn-default.btn-info, .btn.btn-info,
.project-find .btn-group-find .btn, .find-and-replace .btn-group-find .btn,
.update-all-button.btn.btn-primary {
  color: #a9caf1 !important;
  border-color: #a9caf1 !important;
}
.btn.btn-info:hover,
.update-all-button.btn.btn-primary:hover,
.find-and-replace .btn-group-find .btn:hover,
button.btn-info:hover, button.icon.btn-info:hover, .btn-default.btn-info:hover, .btn.btn-info:hover {
  color: white;
  background: #a9caf1 !important;
  border-color: #a9caf1 !important;
}
.settings-view button.install-button.is-installing {
  color: white !important;
  border-color: #a9caf1 !important;
  background: #a9caf1;
}
// Fix notifications to be more Arc-like
atom-notification.success .content {
  background-color: #F5F6F7;
}
atom-notification.success.icon:before {
  color: white;
  background-color: #73d216;
}
atom-notification.warning .content {
  background-color: #FFC8AB;
}
atom-notification.warning.icon:before {
  color: white;
  background-color: #F27735;
}
atom-notification.error .content {
  background-color: #FF655D;
}
atom-notification.error.icon:before {
  color: white;
  background-color: #E7150A;
}
atom-notification.fatal .content {
  background-color: #FF655D;
}
atom-notification.fatal.icon:before {
  color: white;
  background-color: #E7150A;
}
atom-notification.info .content {
  background-color: #a9caf1;
}
atom-notification.info.icon:before {
  color: white;
  background-color: #5294E2;
}
// Fix status bar colors
.text-error {
  color: #E7150A;
}
.linter-highlight.status-success {
  color: #73d216;
}
// Fix checkbox color
.settings-view input[type="checkbox"]:checked {
  background-color: #73d216;
}

I'll have a look at their css.