gtk.css

@define-color window_bg_color #242424;
@define-color window_fg_color #ffffff;
@define-color view_bg_color #1e1e1e;
@define-color view_fg_color @window_fg_color;
@define-color accent_bg_color @blue_3;
@define-color accent_fg_color #ffffff;
@define-color accent_color @blue_4;
@define-color headerbar_bg_color #303030;
@define-color headerbar_backdrop_color @view_bg_color;
@define-color headerbar_fg_color @window_fg_color;
.dim-label {
  opacity: 0.9;
}

decoration {
  box-shadow: 0 3px 12px 1px rgba(0, 0, 0, 0.3), 0 0 0 1px rgba(255, 255, 255, 0.3);
}

decoration:backdrop {
  box-shadow: 0 3px 12px 1px transparent, 0 2px 6px 2px rgba(0, 0, 0, 0.14), 0 0 0 1px transparent;
}

.maximized decoration, .fullscreen decoration {
  box-shadow: none;
}

.tiled decoration, .tiled-top decoration, .tiled-right decoration, .tiled-bottom decoration, .tiled-left decoration {
  box-shadow: 0 0 0 1px rgba(255, 255, 255, 0.3), 0 0 0 20px transparent;
}

.tiled decoration:backdrop, .tiled-top decoration:backdrop, .tiled-right decoration:backdrop, .tiled-bottom decoration:backdrop, .tiled-left decoration:backdrop {
  box-shadow: 0 0 0 1px transparent, 0 0 0 20px transparent;
}

.popup decoration {
  box-shadow: none;
}

.ssd decoration {
  box-shadow: 0 0 0 1px alpha(currentColor,0.5);
}

.ssd decoration:backdrop {
  box-shadow: 0 0 0 1px alpha(currentColor,0.5);
}

.ssd.maximized decoration, .ssd.maximized decoration:backdrop {
  box-shadow: none;
}

.csd.popup decoration {
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.2), 0 0 0 1px alpha(rgba(255, 255, 255, 0.3),0.9);
}

window.csd {
  outline: 1px solid rgba(255, 255, 255, 0.3);
  outline-offset: -1px;
}

window.csd:backdrop {
  outline-color: transparent;
}

headerbar {
  box-shadow: inset 0 -1px rgba(255, 255, 255, 0.5);
  border-bottom: none;
}

headerbar:backdrop {
  box-shadow: none;
}

windowcontrols > button > image:not(:backdrop),
button.titlebutton:not(:backdrop) {
  color: @window_fg_color;
  box-shadow: inset 0 0 0 1px alpha(currentColor,0.5);
}

windowcontrols > button > image:backdrop,
button.titlebutton:backdrop {
  background-color: transparent;
}

windowcontrols > button > image:backdrop:hover,
button.titlebutton:backdrop:hover {
  box-shadow: inset 0 0 0 1px alpha(currentColor,0.5);
}

switch {
  background-color: alpha(currentColor,0.3);
}

switch:hover:not(:checked) {
  background-color: alpha(currentColor,0.4);
}

switch:checked {
  color: @window_fg_color;
  background-color: @accent_bg_color;
}

switch:checked:hover {
  background-image: image(alpha(currentColor,0.1));
}

switch:checked:hover:active {
  background-image: image(rgba(0, 0, 0, 0.2));
}

scale trough:not(:backdrop),
progressbar trough:not(:backdrop) {
  background-color: alpha(currentColor,0.3);
  color: @window_fg_color;
}

scrollbar slider {
  color: @window_fg_color;
  background-color: alpha(currentColor,0.6);
}

scrollbar slider:hover {
  background-color: alpha(currentColor,0.8);
}

scrollbar slider:active {
  background-color: @accent_bg_color;
}

scrollbar.overlay-indicator {
  opacity: 1;
}

notebook > header tab:checked.reorderable-page,
tabbar tab:checked {
  background-color: shade(@headerbar_bg_color,1.2);
  box-shadow: inset 0 -3px @accent_bg_color;
}

notebook > header tab:checked.reorderable-page:backdrop,
tabbar tab:checked:backdrop {
  background-color: @window_bg_color;
  box-shadow: inset 0 -3px shade(@window_bg_color,1.4);
}

.nautilus-list-view .view:selected, .nautilus-list-view .view:selected:hover {
  background-color: @accent_bg_color;
  color: @accent_fg_color;
}